Primary sources involve original research with novel findings or provide firsthand evidence (e.g., photographs, records, official documents).
Secondary sources offer analyses or interpretations of primary source evidence or findings (e.g., journal articles, reviews).
Tertiary sources are reference works that use primary and secondary sources to provide an overview of the topic (e.g., databases, dictionaries).
Some important critical thinking skills are:
APA Style uses sentence-style capitalization for article titles in the reference list, which means only the first word and any proper nouns are capitalized (e.g., “Language production and serial order”).
Sentence-style capitalization is also used for book and webpage titles.
However, for the titles of journals, headline-style capitalization is used. This means all words except prepositions, conjunctions, and articles are capitalized (e.g., Journal of Communications Technology and Electronics).
QuillBot’s free Citation Generator can automatically create APA Style references for you.
In APA references, the titles of books, webpages, and reports are italicized, as are the titles and volume numbers of journals and other periodicals.
The titles of articles or book chapters are not italicized.
QuillBot’s free Citation Generator can automatically create APA Style references for you.
In an APA reference list, page numbers are typically included for journal articles and chapters in edited works. Entries for books and webpages typically do not include page numbers.
| Journal article | Ferrand, C. (2002, December). Harmonics-to-noise ratio. Journal of Voice, 16(4), 480–487. https://doi.org/10.1016/s0892-1997(02)00123-6 |
| Chapter in an edited book | Dillard, J. P. (2020). Currents in the study of persuasion. In M. B. Oliver, A. A. Raney, & J. Bryant (Eds.), Media effects: Advances in theory and research (4th ed., pp. 115–129). Routledge. |
The two numbers in a page range are connected using an en dash (–) rather than a hyphen (-).
QuillBot’s free Citation Generator can automatically create APA Style references for you.
Access dates are not normally required in APA Style in-text citations or references. They are never needed for online journal articles or ebooks.
But, if you create an APA citation for a website that is likely to be updated in the future, you should include an access date. For example:
The University of Texas at Arlington. (n.d.) Our alumni make history. Retrieved May 9, 2024, from www.uta.edu/about/alumni
APA in-text citations of quotations or paraphrases of specific text must include a locator. When no page numbers are available (e.g., when citing a website), you can use paragraph numbers or heading names (or a combination) instead: (Cordero, 2021, Key Facts section, para. 3).
When you refer to the source as a whole, you do not need to include any locator information.
APA in-text citations for online articles or websites include the author’s last name and publication year: (Patel, 2020). Often, the author is an organization: (National Institutes of Health, 2022).
When citing a quotation, you should include some type of locator. This could be a paragraph number (Patel, 2020, para. 10) or section title (Patel, 2020, Future Plans section).
For further information, read our guide on APA website citations.
Using the CRAAP test will help you to assess information critically. This focuses on the currency, relevance, authority, accuracy, and purpose of the information source.
Good questions to ask include:
How you use “et al.” in citations depends on the style guide you are using.
In MLA, “et al.” is used both for in-text citations and the Works Cited page when a source has three or more authors.
In APA 6th edition, works with three to five authors are listed using “et al.” after the first citation. In APA 7th edition, works with three or more authors are listed using “et al.” from the first in-text citation.
In Chicago style, works with four or more authors are listed using “et al.” from the first citation.
Proximity operators, such as NEAR (Nx), WITHIN (Wx), and SENTENCE, can be used along with keywords to filter for results that include the keywords within a certain proximity to each other.
Different proximity operators are used to obtain different results. For example, Wx identifies sources where the keywords occur within a specific number of words (x) of each other and in the order listed.
A Boolean search uses Boolean operators (e.g., “AND,” “NOT”) and keywords to narrow or expand search results. You can use Boolean searches to:
Make sure you have a clear idea of the parameters of your research and the key terms you want to search. Then choose a database that is relevant to your research (e.g., Cochrane, JSTOR, Medline).
Use specific keywords and their variations and synonyms when searching for scholarly sources.
Some databases have a “subject search” option, which can be useful. Become familiar with Boolean operators to efficiently combine keywords, search for exact phrases, and exclude specific terms.
When evaluating sources, vertical reading means reading a source (e.g., a website) to evaluate its credibility.
This is contrasted with lateral reading, which means researching what has been written about the source elsewhere in order to help you evaluate its credibility (e.g., searching for references to a website on other websites that you trust).
When evaluating sources, do a preliminary evaluation of each source before you invest time in an in-depth evaluation:
Academic researchers use a range of credible sources in their works. They will typically cite only their primary and secondary sources. The main types of sources are:
Your research process is likely to include many of these types of scholarly sources, although the sources used will vary according to the goals and topic of your research.
Knowing how to find the credible sources you need is important when conducting research.
Scholarly sources are written by experts in the field of study using technical or academic language. Very often they are peer-reviewed before publication, and they will always have a full bibliography. They are usually considered to be credible sources.
Popular sources are written for a more general audience. They are most likely to be written by journalists and may not have a bibliography. Their language is generally less formal, and they might be written from a biased point of view. This means that these types of sources are not always reliable, but can still be used and cited if appropriate to your research.
When to use et al. in APA in-text citations depends on which edition of the APA Publication Manual you are using.
In APA 6th edition, works with three to five authors are listed using “et al.” after the first citation.
Example: “Freeman, Taylor, and Werg (2024) reject this hypothesis. Instead, their data indicates that the opposite is true (Freeman et al., 2024).”
In APA 7th edition, works with three or more authors are listed using “et al.” after the first author’s name from the first citation.
Example: “Freeman et al. (2024) reject this hypothesis.”
“Ibid.” is included only in footnotes or endnotes and should not be used as an in-text citation. Additionally, not all style guides (e.g., APA, MLA) permit the use of “ibid.”
Once you have included the full citation for a source, “ibid.” can be used to refer back to that source in the next citation. It cannot be used if there are other intervening citations.
Chicago style still permits the use of “ibid.,” but the use of short notes is preferred. In either case, the choice to use “ibid.” or short notes should be consistent.
APA Style, like MLA style, does not permit the use of “ibid.” Both MLA and APA Style use in-text parenthetical citations, and footnotes are used only to add further information, not for citations.
“Et al.” means “and others.” It is used to save space in in-text citations when citing a source with three or more authors; you use it after the first author’s name in place of the remaining names.
Paraphrasing plagiarism happens when someone paraphrases an outside source in a piece of writing without giving credit to the original source.
When you paraphrase ideas from outside sources in your own words, you must show where that information came from in order to avoid plagiarism. Sentences that have paraphrased information should include in-text citations.
An in-text citation includes the author’s name at a minimum, and depending on the citation style you’re using, it might include other elements such as a year of publication or a page number.
For example, APA in-text citations for paraphrases should include the author and year of publication.
You can avoid paraphrasing plagiarism by using QuillBot’s free Plagiarism Checker to look for paraphrases in your writing that need citations.
You can paraphrase a source without plagiarizing by following both of these steps.
APA style paraphrase: According to Ridder (2023), almost two-thirds of adults born after 2000 reported that they never drink coffee.
If you need help paraphrasing a source without plagiarizing, QuillBot’s free Paraphraser can reword excerpts from outside sources. QuillBot’s free Plagiarism Checker will help you find paraphrases in your writing that need in-text citations.
You should paraphrase information instead of using a direct quote when the information that you’re sharing with your readers is more important than the original source’s style of writing.
Use paraphrases to share facts and statistics from outside sources. In this situation, the original author’s wording is less important than the information. Paraphrasing helps you maintain your own writing voice.
Use direct quotes from outside sources in these situations:
Whether you paraphrase or quote another writer’s ideas, use in-text citations to avoid plagiarism.
QuillBot’s free Citation Generator can help you create in-text citations for direct quotes and paraphrases.
You always have to cite a paraphrase in order to avoid plagiarism.
An in-text citation helps your readers differentiate between your original ideas and other writers’ ideas.
The format for in-text citations varies by each citation style (e.g., APA, MLA, or Chicago). In MLA writing, in-text citations should include the author’s last name and the page number where the information is located in the original source.
QuillBot’s free Citation Generator can help you cite a paraphrase in your writing.
The main difference between paraphrasing and summarizing is that paraphrasing involves rewording part of an outside source, but summarizing involves describing what an entire source is mainly about.
A paraphrase rephrases a specific fact, statistic, or idea from an outside source that you’re using as evidence in academic writing.
A summary is a synopsis that describes the main topic and key points of a complete text (e.g., an article) in order to give your readers context about why the source is significant. Summaries are common in literature reviews and annotated bibliographies.
To avoid plagiarism, use your own words anytime you paraphrase or summarize another person’s work in your writing, and give credit to the original source with a signal phrase or an in-text citation.
If you need help with paraphrasing and summarizing, QuillBot’s free Paraphrasing Tool can reword ideas from another source. QuillBot’s free Citation Generator can also help you create in-text citations.
Chicago style has two citation formats: notes and bibliography and author-date.
Notes and bibliography is the more common format. In it, footnotes are used in the body of the text, and a bibliography is included at the end. A full note is used the first time a source is cited and a shortened note (with only author, title, and page number) thereafter.
| Full footnote | 1. Robin Wall Kimmerer, Gathering Moss: A Natural and Cultural History of Mosses (Penguin UK, 2021), 22–25. |
| Shortened footnote | 2. Kimmerer, Gathering Moss, 22–25. |
| Bibliographic entry | Kimmerer, Robin Wall. Gathering Moss: A Natural and Cultural History of Mosses. Penguin UK, 2021. |
In author-date format, parenthetical citations are used instead of footnotes. The in-text citation includes the author’s last name and date (e.g., Kimmerer 2021). A full bibliography is included at the end.
To cite a text in an APA parenthetical citation, list the author’s last name, the publication year, and page number, all separated by commas.
Example: (Smith, 2014, p. 67)
QuillBot’s Citation Generator can help you quickly generate citations in APA, MLA, and Chicago style formats.
Secondary sources include textbooks, journal or newspaper articles, reviews, essays, or biographies.
Secondary sources summarize, analyze, and interpret primary sources. Sources that provide an overview on a topic or give another researcher’s views are generally secondary sources.
To evaluate whether a source is a primary or secondary source, ask the following questions:
Some sources generally always serve as primary sources. These include artworks and literature, raw statistics, official documents and records, and personal communications such as journal entries or interviews.
Primary sources are generally considered the most credible evidence to use to support an argument because they are directly involved with the research subject. However, you should still vet these sources for reliability and accuracy.
All sources you use must be accompanied by a citation to avoid plagiarism. You can use QuillBot’s Citation Generator to automatically generate citations for all types of sources.
Primary sources include statistical data, speeches, transcripts, photographs or videos, original artistic or literary works, and historical documents.
If you analyze something directly, it functions as a primary source. This includes your own original quantitative or qualitative data.
In-text citations should always come before punctuation, including periods, commas, semicolons, and dashes. You can include a citation mid-sentence or at the end of the sentence.
To cite an indirect source in APA in-text citations, include the author name and date where available, followed by “as cited in” and the author name and date of the secondary source you are using.
Parenthetical: (Weber, 2010, as cited in Baqqa, 2016)
Narrative: Weber (2010, as cited in Baqqa, 2016) claims that …
Page numbers are only necessary in APA in-text citations when material is directly quoted. Include the page number after the publication date (Author, date, p. 1).
To cite a page range, include “pp.” and use an en dash (Author, date, pp. 1–10).
Biographies are generally secondary sources as they present information about the life of someone else. The author will likely consult primary sources to compose the biography, such as personal letters, archival records (e.g., birth registries), or diaries. In contrast, an autobiography is a primary source as it is a firsthand account of one’s own life.
However, if you are researching the ways in which a particular figure’s life has been represented, then biographies written about the person would function as primary sources.
Any time a biography or other source is used, it must be accompanied by a citation and reference entry to avoid plagiarism. You can use QuillBot’s Citation Generator to automatically generate citations for all types of sources.
An APA parenthetical citation includes the author’s name, publication date, and page number(s) within parentheses. In APA Style, a narrative citation has the author’s name in the sentence and the date of publication in parentheses.
Example: In As I Lay Dying, Faulker illustrates the effects of death on the living (1930).
QuillBot’s Citation Generator can help you quickly generate citations in APA, MLA, and Chicago style formats.
A parenthetical citation is an in-text citation within a set of parentheses. It includes source information like the name of the author, publication date, and page number(s). It will usually come at the end of a sentence before the punctuation mark.
Parenthetical citations vary depending on the citation style (e.g., APA, MLA, Chicago).
QuillBot’s Citation Generator can help you quickly generate citations in APA, MLA, and Chicago style formats.
A quote is a direct copy of another person’s words and must be enclosed in quotation marks.
Paraphrasing is a summary or rephrasing of another person’s words without using the exact language.
Both quoted and paraphrased material must be accompanied by a citation to avoid plagiarism.
The information contained in a citation depends on the style guide you are following.
Essentially, in-text citations must contain the necessary information for a reader to be able to identify the complete citation in your reference list.
Quotes are a valuable tool for enhancing your argument and adding additional support for your claims. However, it is important to avoid overusing quotes, as this can cause your own voice to be lost.
When you use quotes in academic writing, accompany them with analysis and explanation, and do not include quotes for information that you can present in your own words.
To cite information from a footnote in an MLA in-text citation, include the author’s name and page number as usual, followed by “n” and the footnote number (Bing 205n4).
To cite multiple footnotes, use “nn” and an en dash with the number range (Bing 205nn4–8).
For footnotes without numbers, include a space after the page number followed by “un” (Bing 103 un).
MLA in-text citations must be included any time you quote or paraphrase another source. Failing to include a citation could result in accidental plagiarism.
Citations are not usually needed for generally available knowledge, such as the dates of historical events or the birthdates of historical figures.
Newspaper and magazine articles can function as primary or secondary sources depending on how you use them for your research.
In a historical study, for example, you might use contemporary newspaper articles as direct evidence of the time period. In social and communication studies, you might examine the language or content of an article to glean insights into the particular phenomenon under study (e.g., through a content analysis or discourse analysis).
If you are using an article to furnish background information or facts about the topic, the article functions as a secondary source.
Any articles you use should be cited appropriately and included in your references list. You can use QuillBot’s Citation Generator to automatically generate citations for all types of sources.
Strong academic research requires engagement with information from other researchers, but this is only valid when the sources used are accurate. Online information and published articles may exhibit bias, lack credibility, or lack evidence to support their claims.
Information literacy denotes the range of skills you need to be able to decipher the credibility of a source. Information literacy and critical thinking are fundamental to academic research and responsible media consumption more broadly.
Sources can be vetted using the CRAAP test as well as checked for the following points to ensure credibility:
Quillbot’s Citation Generator tool can help you to create and manage your citations throughout the research process.
You should always include a citation for the sources you use to support any academic text.
In-text citations must accompany any material that is quoted, paraphrased, or summarized. The in-text citation should direct the reader to the full reference entry in the references list or bibliography.
The format of your citations and reference entries is determined by the citation style you are using (e.g., MLA, APA, Chicago).
Quillbot’s Citation Generator can help you to create and manage your citations throughout the research process.
Wikipedia is not generally considered a credible source on its own. This is because Wikipedia is an open-access platform that anyone can edit at any time. Thus, while Wikipedia can be helpful when just starting out in your research, it should not be cited among your sources in your final paper.
However, you can use the references cited in Wikipedia articles to access the research materials the articles are based on. If a Wikipedia article cites academic sources such as journal articles, go directly to these sources to perform more in-depth research. These sources can be used to support your paper.
Tertiary sources are generally not cited directly in academic writing. However, they can be useful as a jumping-off point when you begin the research process.
When you’re starting your research, you can use tertiary sources to:
Tertiary sources can direct you to primary and secondary sources that you can use later during the writing process.
Your research problem and the way you use a source will determine whether it is tertiary.
The following questions can help you evaluate whether something is a tertiary source:
Signal phrases have a variety of functions. They can be placed at the beginning, middle, or end of a sentence.
When using signal phrases to integrate another author’s ideas, words, or data, include:
The verb tense you use in your signal phrase depends on the style guide you are following.
Signal phrases are used to attribute information to the original source. This is important as it enables you to:
The type of signal phrase you use provides information about your or the original author’s position on the point presented. Signal phrases can indicate agreement, disagreement, doubt, and other relationships between authors’ stances.
Common signal phrases to indicate agreement include “confirms” or “supports” (e.g., “Smith’s works confirms the prevailing view”).
Common signal phrases to indicate disagreement include “denies” or “refutes” (e.g., “Attorney Marta Resnick denies that there is any credible evidence pointing to her client”).
Neutral signal phrases include “states” or “observes” (e.g., “Liu and Gray observe that …”).
Academic journals use peer review processes to evaluate submissions for publication. Experts in the subject area use defined criteria to measure the quality of a text and determine suitability for publication.
The peer review process results in high-quality publications, which is why academic journals are often considered the most credible sources.
If a source doesn’t use a peer review process, you can use the CRAAP test to determine whether it is credible.
The “Accuracy” component of the CRAAP test for evaluating sources refers to whether the information in a source is correct, factually based, and supported by evidence. Consider where the information has come from and the source itself. For example, was it published by a reputable source, and are you able to verify the claims?
The “Relevance” component of the CRAAP test for evaluating sources refers to whether the information in a source is related to your research subject. Consider if the information adds something to your argument and whether the information is intended for a specialized audience.
Researchers use many different types of sources, including:
The types of source you use might change as you make progress through the research process.