APA style requires you cite every reference or source within your essay or thesis paper. For in-text citation, depending on the manner in which the sentence has been constructed, the author’s last name and the year of publication should be included
APA In-Text Citation Single or One Author Printed Book
Citing the author’s name as part of a sentence (APA 6th, p. 174). If the name of the author appears in the sentence itself, cite only the year in parenthesis
In her study, Smith (2011) found that one of every three dogs is morbidly obese.
Jones (1997) finds a genetic link to alcoholism.
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Jones (2001) also found …
Jones (2001) examines the effectiveness of …
A potential connection was found between DNA damage and the immunostimulatory cytoking IL-12 in a recent study by Schwarz (2002).
In his recent study, Shwarz (2002) indicated a potential connection between DNA damage and the immunostimulatory IL-12.
Variations in in-text citations (APA 6th, pp. 174-179). If the author’s name does not appear in the sentence, cite the author’s last name followed by a comma and the year in parenthesis. Include in-text citation at the end of the sentence.
In one study, it was found that one in three dogs is morbidly obese (Smith, 2011).
One recent study finds a genetic link to alcoholism (Jones, 1997).
In a recent study of the effects of high protein diets (Jones, 2001)…
If you have used the author’s last name and the year of publication in the same sentence, no parenthethical citation is necessary
In her 2011 study of obesity in dogs, Smith concluded that one in three dogs is morbidly obese.
In 2001, Jones’s study of high protein diets found that …
For subsequent mentions if the citation is part of the text, date the source in the first citation in a paragraph (APA 6th, p. 174). You need not include the year in subsequent citations in the same paragraph. If you start a new paragraph then again include the year in the first citation in that paragraph.
In a recent study of reaction times, Brown (2002) described the method … Brown also finds …
APA End Reference Citation Single or One Author Printed Book
APA style requires you list all of the references you have used and cited within your paper in a separate Reference section. The Reference list gives readers the means of finding all of your references in one place
Last Name, Initials of First Name and Middle Name. (yyyy published). Title of book. Place of Publication: Publisher.
Johnson, R. A. (2009). Helping fat wolverines. New York: WolverineBooks.
Moore, T. I. (1971). Social patterns in Australian Literature. Sydney,
Australia: Angus & Robertson.