The following elements are common to include in a citation for typical sources such as books and articles, respectively (although, depending on the source, additional information may be required):
For a book:
- Author
- Year of publication
- Title of book
- Publisher
- If it's from an electronic source, then a DOI number, if available
For an article in a print magazine or journal:
- Author(s)
- Date of publication (Year; Month Year; or Year, Month Day)
- Title of Article
- Title of Publication (Magazine or Journal name)
- Volume number (corresponds to the year)
- Issue number (corresponds to month/day, but is not always required)
- Page numbers
- If it's from an electronic source, then a "DOI" link (which stands for "Digital Object Identifier"), if available--otherwise, it looks just like a citation to a print journal article.
Now take a look at Step 6 (below to the right or in the left sidebar) to see examples and explanations of APA citations.