How should I present the date in my references in APA style, including if no date is available?
In general, “give in parentheses the year the work was published” (American Psychological Association, 2010, p. 185). Please refer to page 185 in the APA manual for more information regarding presenting the publication date of resources, including magazines, newsletters, and newspapers, as well as in-press publications and papers and posters presented at meetings. For sample references, search WriteAnswers for the resource type. If it’s appropriate to provide the full date of publication, the order of information in is (year, Month day) without any abbreviations or suffixes: (2013, October 31). For resources where no date is available, use (n.d.), which stands for “no date” (p. 185). For information on how to cite multiple sources with the same author and no publication date, please see "How do I cite in-text two or more resources by the same author that were published in the same year in APA style?".
American Psychological Association. (2010). Publication manual of the American Psychological Association (6th ed.). Washington, DC: Author.