Note: Changes in the sixth edition of the Publication Manual of the American Psychological Association are highlighted below
According to the sixth edition of the APA manual, when available, you should include the DOI (digital object identifier) for print and electronic sources in the reference entry. The DOI number is placed at the end of the entry without ending punctuation:
Author, A. A., & Author, B. B. (Date of publication). Title of article. Title of Journal, volume number. doi:0000000/000000000000
When a DOI is not available, and a URL is included, do not include retrieval dates unless the source material may change over time (e.g., wikis). When citing an entire website (when you are not quoting from, but rather making reference to an entire website), it is sufficient to give the address of the site in just the text (no entry in the reference list is necessary). In general, it is not necessary to include database (ERIC, JSTOR, OVID) information.
If the document is composed of multiple web pages, give the URL of the home page or entry page for the document. If no publication or "last modified" date is apparent, use n.d. in place of the publication date.
Give chapter or section numbers (if available) in place of page numbers. Provide the URL that points to the first page of the chapter or section you are citing.
When citing books or chapters only available online, the electronic retrieval statement replaces the publisher location and name.
Provide the URL of the newspaper home page when the online version of the article is available by search to avoid nonworking URLs.
If the online version refers to an existing print edition, include the edition number of the print version after the title.
For a motion picture, the first executive producer and the first director should be listed as the responsible parties. If one of these parties fulfilled multiple creative roles in the film, all such roles should be listed. If credits for director and producer are not available, provide the name of the individual or organization most responsible for the work.
Do not italicize the names of software, programs, or languages. Include the version number (if any) in parentheses immediately after the title. Also, provide the location and name of the organization that produced the work (if applicable).
NOTE: For the following three entries, Provide the author's full name (if available) in the form of last name followed by first initials. If only a screen name is available, provide the screen name in place of the author. Include the exact date of the posting followed by the subject line of the message or "thread." Also, if available, provide the name of the list to which the message was posted if this information is not already included in the URL.