According to APA style

Source citation in academic texts always consists of two things: 1) in-text source citations and 2) a bibliography with all your complete references. In the running text, when citing information, you briefly indicate which source the information comes from. What exactly does a source citation in the text look like in APA style? We will tell you what the guidelines are, and show you some examples (and exceptions). 

According to APA style, an in-text source citation consists of the author's last name and the year of publication. You may add a page number (or page numbers) to this if you are citing a particular part of the source or directly quoting a specific text. 

For example, this looks like:

• Janssens (2019, p. 50) says the following about this: "..."

• Around 30% of students are not satisfied with the menu in the university cafeteria, according to research by Pieters and Cornelissen (2021). 

• Much is already known about the effects of houseplants on your productivity. For example, plants have been shown to improve your concentration (Franken, 2017), to make the air quality in the room healthier (Kamerik, & Janssens, 2019), and to make people feel less tired with plants in the home (Willemsen, & Van Dijk, 2020). 

What you probably already notice in these examples is that some references are in parentheses and others are in the running text. Both variations are possible. If you mention the author in the running text, put the year (possibly followed by page numbers) in parentheses. If you do not mention the author in the sentence itself, put the author, year, and possibly the page numbers in parentheses after the information coming from this source.

Do you refer to different authors in the running text? Then the following rules apply:

• When usingparentheses, put an ‘&’ sign between the surnames. 

• When referring directly in the text itself, put the word "and" between the surnames. 

• When referencing three or more authors, list only the last name of the first author and put "et al." after it. (In the bibliography, you must include all authors, up to a maximum of twenty authors.)

• Is the author an organization (such as the Chamber of Commerce, RIVM or CBS)? If so, write out the abbreviation the first time you use it. The times after that, you can use the abbreviation to refer to this organization.

Chances are you will refer to the same source several times. In that case, you don't have to cite the source in every sentence. For example, if you make it clear in sentence 1 of a paragraph that you are going to discuss a study by a particular author, then you do not need to keep repeating that author after that. Are you citing verbatim quotes from this research article? If so, an additional source statement in the text accompanying those quotes is required. 

It is important not to understate sources. If you refer to the same source a few pages later in the text, you should still cite the source again. Do you refer to the same source several times in a row? Then you don't have to mention the year, but it is useful to regularly drop the author's name.

Are you citing a quotation? Then, always include the author's name, the publication year, and the page number the quotation came from. Here, use "p. preceding the page number. Is the citation from multiple pages? Then use 'pp.' .

Is the quote in the running text, and does the source citation follow in parentheses? Then, mark the quote with double quotation marks and put the source citation immediately after the quote. For example:

Research shows that "perfectionism is a common problem among young people, due in part to social media use" (Staats & Wezel, 2018, p. 85). 

Do you include the citation in the sentence itself? Then, you can also name the authors of the quote in the running text and put the year of publication in parentheses behind it.  Then, you list the page number after the citation. This looks like:

Staats and Wezel (2018) state that "perfectionism is a common problem among young people, due in part to the use of social media" (p. 85). 

Are you quoting a quote of more than 40 words? Then, put the quote between two blank lines and indent it in the margin. The source should be cited in full in parentheses on the last line of the quotation. In doing so, name the author, year, and page number.

What if you want to edit a quote? 

A quote is a literal copy of someone else's words. However, sometimes you may want to change a few words or omit part of it to fit the context. These kinds of changes should always be indicated with square brackets. Are you excluding something? Then, put three dots between square brackets where the fragment was removed from. 

In practice, for example, this looks like this:

• However, Janssens (2018) believes that "this is not fair [toward] scholars" (p. 115).

• In his dissertation, Pietersen (2011) gives the following definition of perfectionism: "the urge to perfect something to the smallest detail [...], more because you yourself think it should be perfect than because it is expected of you" (p. 92).

Sometimes you can’t find certain information about the source. For example, a web page sometimes lacks an author or date. In such cases, the source citation in the text looks slightly different. These examples will give you a good idea of what to do:

The author is missing

Is the author missing? Then, put the title of the source and the year in parentheses. Thus:

(Title of source, 2023)

Note that if a document is written by an organization, you include that organization as the author. You don't have to give the title of the source in that case. The source then looks something like this:

(Central Bureau of Statistics, 2022)

The date is missing

If you don't know the date of publication, use the abbreviation "n.d." This stands for "no date." It looks like this:

(Wessels, n.d.)

The page number is missing

Are you including a citation, but do not know the page number? Then, there are other things you can do to  indicate where the information came from. For example, in videos or podcasts, you can sometimes refer to the timestamp that the quote is said. In books or on publications, you can sometimes refer to a chapter or paragraph number. In other cases, you can omit the page number. 

A few examples:

• (Van der Sanden, 2022, para. 5)

• (Zinkman, 2019, Slide 3)

• (The Camp, 2016, 02:58)

• (Wessels, 2021)

Note: Are you referring to the Bible, Koran, or Torah? If so, always include the chapter and verse number in the reference. These are used instead of any page numbers.

Sometimes you want to support a statement with multiple sources. In that case, you can put those different sources in the same parentheses. Always put a semicolon between the sources and sort them in alphabetical order . 

Do you cite multiple sources from the same author? Then, list the different years of publication after the author. Distinguish those years with a comma. 

It looks like this:

• This has already been demonstrated by several studies (De Vries, 2019; Peters, & Levelt, 2005; Ysbrand & De Lange, 2017).

• Children benefit when their parents begin reading aloud as early as infancy (Strietman, 2019, 2021).

• Research by Strietman (2019, 2021) shows that it is beneficial for children when their parents start reading aloud as early as infancy. 

Sometimes the same author has published several sources in one year and you want to cite them both. In that case, put letters like a, b, c, etc. after the year. You then get, for example:

• (De Wit, 2016a)

• (The W it, 2016b)

In such a case, also keep the letters a, b, etc. in the bibliography. 

What if several authors have the same last name? 

Are you referring to two different authors with the same last name? Then put the author's initials in the reference. This then becomes:

• (J. De Wit, 2019)

• (B. De Wit, 2016)

Applying the APA rules correctly is quite a challenge,  especially the bibliography, which of course must also be formatted according to the rules. Are you afraid of making mistakes? The AthenaCheck editors are happy to do an extensive source check for you. This way, you can be sure that your source citation is correct. 

Or, you can have a plagiarism check done on your thesis. This will prevent you from unknowingly committing plagiarism.