According to APA style guidelines, internal citations, instead of footnotes or endnotes, should be used to document sources. Internal citations are parenthetical and include the author's last name and the year of publication, separated by a comma. The exception is if the author name is used in the sentence, in which case the parenthetical should only include the year of publication. When paraphrasing an idea, no page number is required. However, when quoting directly from a work, the parenthetical citation should also indicate a page number.
If an author is unknown, the source is cited by its title or by the first word or two. Titles are italicized or underlined, but not both. Titles of articles, chapters, Web pages or shorter works within other titled works are placed in quotation marks. If a work contains two authors, both authors should be cited by last name, separated by "and" if in a sentence or an ampersand if in parenthetical citation.
For works by three to five authors, list all authors the first time and, in subsequent citations, use only the first author's last name followed by "et al." For works by six or more authors, use only the first author's last name followed by "et al." in all instances.
A reference list must appear at the end of the document. The purpose of the reference list is to provide full bibliographic citations for each and every source cited internally throughout the text. Importantly, the reference list should not include any sources not cited in the text --- such as works only consulted.
Reference lists are organized alphabetically by author last name. Basic references should include, in the following order, the author's full name, the year of publication, the title of the work, location and publisher. When listing books, chapter, articles and Web pages, only capitalize the first letter of the first word or the title and the subtitle, if one exists. However, all major words in journal titles should be capitalized.
APA guidelines for punctuation are similar to MLA and Chicago with a few exceptions. For instance, a serial comma is not used. A serial comma is the comma that precedes the conjunction in a series or list consisting of three or more items. Also, only one space follows a period before beginning a new sentence. Numerical values should not incorporate commas. For instance, use "1500 miles" rather than "1,500 miles."