In-Text Citations: Author/Authors

Note: This page reflects the latest version of the APA Publication

Manual (i.e., APA 7), which released in October 2019. The equivalent
resource for the older APA 6 style can be found here.
Though the APA's author-date system for citations is fairly straightforward,
author categories can vary significantly from the standard "one author, one
source" configuration. There are also additional rules for citing authors of
indirect sources, electronic sources, and sources without page numbers.
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A Work by One Author 

The APA manual recommends the use of the author-date citation
structure for in-text citation references. This structure requires that any in-
text citation (i.e., within the body of the text) be accompanied by a
corresponding reference list entry. In the in-text citation provide the
surname of the author but do not include suffixes such as "Jr.". 
As Ahmed (2016) mentions... 
(Ahmed, 2016)
Citing Non-Standard Author Categories

A WORK BY TWO AUTHORS

Name both authors in the signal phrase or in parentheses each time you
cite the work. Use the word "and" between the authors' names within the
text and use the ampersand in parentheses.
Research by Wegener and Petty (1994) supports...
(Wegener & Petty, 1994)

A WORK BY THREE OR MORE AUTHORS

List only the first author’s name followed by “et al.” in every citation, even
the first, unless doing so would create ambiguity between different sources.
(Kernis et al., 1993)
Kernis et al. (1993) suggest...
In et al., et should not be followed by a period. Only "al" should be followed
by a period.
If you’re citing multiple works with similar groups of authors, and the
shortened “et al” citation form of each source would be the same, you’ll
need to avoid ambiguity by writing out more names. If you cited works with
these authors:
Jones, Smith, Liu, Huang, and Kim (2020)
Jones, Smith, Ruiz, Wang, and Stanton (2020)
They would be cited in-text as follows to avoid ambiguity:
(Jones, Smith, Liu, et al., 2020)
(Jones, Smith, Ruiz, et al., 2020)
Since et al. is plural, it should always be a substitute for more than one
name. In the case that et al. would stand in for just one author, write the
author’s name instead.

UNKNOWN AUTHOR
If the work does not have an author, cite the source by its title in the signal
phrase or use the first word or two in the parentheses. Titles of books and
reports are italicized; titles of articles, chapters, and web pages are in
quotation marks. APA style calls for capitalizing important words in titles
when they are written in the text (but not when they are written in reference
lists).
A similar study was done of students learning to format research papers
("Using Citations," 2001).
Note: In the rare case that "Anonymous" is used for the author, treat it as
the author's name (Anonymous, 2001). In the reference list, use the name
Anonymous as the author.

ORGANIZATION AS AN AUTHOR
If the author is an organization or a government agency, mention the
organization in the signal phrase or in the parenthetical citation the first
time you cite the source, just as you would an individual person.
According to the American Psychological Association (2000),...
If the organization has a well-known abbreviation, you may include the
abbreviation in brackets the first time the source is cited and then use only
the abbreviation in later citations. However, if you cite work from multiple
organizations whose abbreviations are the same, do not use abbreviations
(to avoid ambiguity).
First citation: (Mothers Against Drunk Driving [MADD], 2000)
Second citation: (MADD, 2000)
TWO OR MORE WORKS IN THE SAME PARENTHESES
When your parenthetical citation includes two or more works, order them
the same way they appear in the reference list (viz., alphabetically),
separated by a semi-colon.
(Berndt, 2002; Harlow, 1983)
If you cite multiple works by the same author in the same parenthetical
citation, give the author’s name only once and follow with dates. No date
citations go first, then years, then in-press citations.
(Smith, n.d., 1995, 2002, in press)

AUTHORS WITH THE SAME LAST NAME

To prevent confusion, use first initials with the last names.
(E. Johnson, 2001; L. Johnson, 1998)

TWO OR MORE WORKS BY THE SAME AUTHOR IN THE SAME YEAR

If you have two sources by the same author in the same year, use lower-
case letters (a, b, c) with the year to order the entries in the reference list.
Use the lower-case letters with the year in the in-text citation.
Research by Berndt (1981a) revealed strong correlations. However, a
parallel study (Berndt, 1981b) resulted in inconclusive findings.

INTRODUCTIONS, PREFACES, FOREWORDS, AND AFTERWORDS

When citing an Introduction, Preface, Foreword, or Afterword in-text, cite
the appropriate author and year as usual.
(Funk & Kolln, 1992)

PERSONAL COMMUNICATION
For interviews, letters, e-mails, and other person-to-person communication,
cite the communicator's name, the fact that it was personal communication,
and the date of the communication. Do not include personal communication
in the reference list.
(E. Robbins, personal communication, January 4, 2001).
If using a footnote to reference personal communication, handle citations
the same way.
1. P. Smith also claimed that many of her students had difficulties with APA
style (personal communication, November 3, 2002).

TRADITIONAL KNOWLEDGE OF INDIGENOUS PEOPLES

When citing information you learned from a conversation with an
Indigenous person who was not your research participant, use a variation
of the personal communication citation above. Include the person’s full
name, nation or Indigenous group, location, and any other relevant details
before the “personal communication, date” part of the citation.
(Caroline Jennings, Cherokee Nation, lives in Tulsa, Oklahoma, personal
communication, October 2019) 

CITING INDIRECT SOURCES

Generally, writers should endeavor to read primary sources (original
sources) and cite those rather than secondary sources (works that report
on original sources). Sometimes, however, this is impossible. If you use a
source that was cited in another source, name the original source in your
signal phrase. List the secondary source in your reference list and include
the secondary source in the parentheses. If you know the year of the
original source, include it in the citation.
Johnson argued that...  (as cited in Smith, 2003, p. 102).
(Johnson, 1985, as cited in Smith, 2003, p. 102).

ELECTRONIC SOURCES
If possible, cite an electronic document the same as any other document by
using the author-date style.
Kenneth (2000) explained...

UNKNOWN AUTHOR AND UNKNOWN DATE

If no author or date is given, use the title in your signal phrase or the first
word or two of the title in the parentheses and use the abbreviation "n.d."
(for "no date").
Another study of students and research decisions discovered that students
succeeded with tutoring ("Tutoring and APA," n.d.). 

SOURCES WITHOUT PAGE NUMBERS

When an electronic source lacks page numbers, you should try to include
information that will help readers find the passage being cited. Use the
heading or section name, an abbreviated heading or section name, a
paragraph number (para. 1), or a combination of these.
According to Smith (1997), ... (Mind Over Matter section, para. 6).
Note: Never use the page numbers of webpages you print out; different
computers print webpages with different pagination. Do not use Kindle
location numbers; instead, use the page number (available in many Kindle
books) or the method above. 
OTHER SOURCES
The APA Publication Manual describes how to cite many different kinds of
authors and content creators. However, you may occasionally encounter a
source or author category that the manual does not describe, making the
best way to proceed unclear.
In these cases, it's typically acceptable to apply the general principles of
APA citation to the new kind of source in a way that's consistent and
sensible. A good way to do this is to simply use the standard APA
directions for a type of source that resembles the source you want to cite.
For example, a sensible way to cite a virtual reality program would be to
mimic the APA's guidelines for computer software.
You may also want to investigate whether a third-party organization has
provided directions for how to cite this kind of source.

(https://owl.purdue.edu/owl/research_and_citation/apa_style/apa_formattin
g_and_style_guide/in_text_citations_author_authors.html)