Throughout the text, you must always include a proper parenthetical reference (author and the year) unless it is within the same paragraph. Within a paragraph, you do not need to include the year in subsequent references to a study. However, you would need to include the year if the study could be confused with another study cited in the same paragraph. e.g.
In 2000, Smith compared reaction times ... OR
Smith (2000) compared reaction times ... OR
In a recent study of reaction times (Smith, 2000) ...
When PARAPHRASING or referring to an idea contained in another work, APA encourages but does not require one to “provide a page or paragraph number, especially when it would help an interested reader locate the relevant passage in a long or complex text.” (Publication manual, 2010, p. 171)
Where there are TWO AUTHORS, cite both names each time the reference occurs in the text. e.g.
The most recent study (Smith & Jones, 1983) ...
When there are THREE TO FIVE AUTHORS, cite all the names the first time. From then on, use only the first name followed by et al. (Latin abbreviation for "and others"). e.g.
First citation: Sokolowski, Smith, Jones and Hajid (1983) discovered that ...
Later citations: Sokolowski et al. (1983) also discovered that ...
When there are SIX OR MORE AUTHORS, cite only the surname of the first author followed by et al. and the year for all citations in text. e.g.
First citation: Hewitt et al. (2001) demonstrated that ...
Later citations: ... as has been shown by Hewitt et al. (2001).
Write out in full the whole name of a GROUP OR ORGANIZATION THAT SERVES AS AUTHOR every time, unless the abbreviation is well known. e.g.
First citation: The police report (Royal Canadian Mounted Police, 1979) ...
Later citations: The RCMP report (1979) ...
Where there is NO AUTHOR, cite the first few words of the title and the date. Put quotation marks around an article title, but italicize the title of a periodical or book. Words in the title are capitalized in reference citations, but not in the reference list. e.g.
A Time magazine article ("Brain Breakthrough," 1988) said that ...
It states in the Vancouver Social Services Directory (1988) ...
When there are TWO OR MORE AUTHORS WITH THE SAME SURNAME, include initials to avoid confusion. e.g.
Both G. A. Jones (1984) and B. W. Jones (1986) have studied ...
When there are TWO OR MORE WORKS BY THE SAME AUTHOR IN THE SAME YEAR, "identify works by the same author (or by the same two or more authors in the same order) with the same publication date by the suffixes a, b, c, and so forth, after the year; repeat the year. The suffixes are assigned in the reference list, where these kinds of references are ordered alphabetically by title (of the article, chapter, or complete work). e.g.
several studies (Derryberry & Reed, 2005a, 2005b, in press-a; Rothbart, 2003a, 2003b) (Publication manual, 2010, p. 178)
PERSONAL COMMUNICATIONS (e.g., emails, memos, private letters, telephone conversations, personal interviews etc.) do not provide recoverable data. They are cited in the text only, not in the reference list. Provide the communicator’s initials and surname and as exact a date as possible. e.g.
The methodology is based on neuroscientific research and demonstrates that it is possible to help students strengthen the weak cognitive capacities underlying their learning dysfunctions (V. Tool, personal communication, May 18, 2011).
When the DATE IS UNKNOWN, use the abbreviation ‘n.d.’ – for ‘no date’. e.g.
Bengston (n.d.) shows that …
When multiple studies support what you have to say, you can include multiple citations inside the same set of parentheses. Within parentheses, alphabetize the studies as they would appear in the reference list and separate them by semicolons. In running text, you can address studies in whatever order you wish. Here are two examples:
Studies of reading in childhood have produced mixed results (Albright, Wayne, & Fortinbras, 2004; Gibson, 2011; Smith & Wexwood, 2010).
Smith and Wexwood (2010) reported an increase in the number of books read, whereas Gibson (2011) reported a decrease. Albright, Wayne, and Fortinbras (2004) found no significant results. (APA Style Blog, 2014)
Incorporate a short quotation (fewer than 40 words) into the text of your essay and enclose the quotation in double quotation marks
Miele (1993) found that "the placebo effect, which had been verified in previous studies, disappeared when only the first group's behaviors were studied in this manner" (p. 225).
Display a quotation of 40 or more words in a freestanding block of typewritten lines and omit the quotation marks.
Miele (1993) found the following:
The placebo effect, which had been verified in previous studies, disappeared when behaviors were studied in this manner. Furthermore, the behaviors were never exhibited again, even when real drugs were administered. Earlier studies were clearly premature in attributing the results to a placebo effect. (p. 255)
Online documents often do not provide page numbers. If the document does not give page numbers but gives paragraph numbers, include them using the abbreviation para.
e.g. (para. 4).
If the document "includes headings and neither paragraph nor page numbers are visible, cite the heading and the number of the paragraph following it to direct the reader to the location of the quoted material".
e.g. (Discussion section, para. 1).
"In some cases in which no page or paragraph numbers are visible, headings may be too unwieldy to cite in full. Instead, use a short title enclosed in quotation marks for the parenthetical citation."
e.g. (Golan, Kuchler, & Krissof, 2007, "Mandatory Labeling Has Targeted", para. 4).
(The heading was "Mandatory Labeling Has Targeted Information Gaps and Social Objectives.")
(Publication manual, 2010, p. 172)