For citing a source within the text, the APA has original grammatical instructions that must be followed in order to adhere to the style. Capitalize all proper nouns and initials, and a reference to a source within your paper should have all words four letters or longer capitalized. However, words shorter than four letters that are nouns, pronouns, adjectives, verbs or adverbs should also be capitalized. Also, capitalize both words in a hyphenated compound word, and capitalize the first word after a colon. Italicize or underline the titles of long works such as books, and use quotations for shorter works such as articles.
When you directly quote a work, you must include the name of the author, the year the work was published and the page number of the quote following "p." If the author is mentioned as a signal phrase preceding the text, the year follows the author's name and the page number follows the quote outside the quotations, while the period follows the page number. For example: "Based on the opinion of McClendon (2004), 'It is standard for students to take notes in class'" (p. 37)." For quotes longer than 40 words, remove the quotations and place the text in a free-standing block format. The entire block of text should be indented 1/2 inch, and any subsequent paragraphs should be indented another 1/2 inch. Place the page number in line with the text at the end of the quote. If you're paraphrasing text, you are only required to cite the author and year of publication, though citing the page number is also suggested.
The first time you cite a source, you should always reference the author's name either in a signal phrase or in parentheses after you quote the text. In a work by two authors, separate their names by "and" in a signal phrase and use an ampersand in your citation, followed by the year of publication. For three to five authors, separate their names by a comma and the last two names by an ampersand. For example: "Bivens, McClendon, Morris, Johnson & Randal, 1987)." In subsequent uses of the text with three to five authors, cite only the first author's name followed by "et al." and the year of publication. For six or more authors, use only the first author's name followed by "et al." and the year of publication in every citation.
If the author of the text is unknown, cite the name of the text in a signal phrase or the first word or two of the text in parentheses, followed by the year of publication. If the author is an organization, simply reference the organization the same way you would reference one author. If the organization has a well-known abbreviation -- FBI for the Federal Bureau of Investigation, for example -- you may use it. To cite two sources in the same citation, reference the authors' last names and the year of publication separated by a semicolon. When citing authors with the same last name, specify by using their first initials. For multiple works by the same author in the same year, specify by adding a, b, c, etc., to order the citations. Introductions, prefaces, forewords and afterwords require a normal citation. Personal communication such as emails, phone calls and other types of interviews requires the subject's name, the words "personal communication" and the date, each separated by a comma.
If you use an indirect source -- a source that was cited in another source -- precede your citation with the words "as cited in." If an author is presented with an electronic source, it should be cited the same as a print source. For an electronic source that has no credited author, use information that will help readers find the source text. If paragraphs are numbered, use the abbreviation "para." followed by the paragraph number. If paragraphs are not numbered, cite the header of the section.