Some databases will automatically generate a citation for the articles included in your search results.  In CINAHL, for example, you can do this by running a search, finding a citation that looks useful, clicking on the article title in that citation and clicking the Cite button, which looks like this:

When you do, a pop up window will appear with the article cited in a number of different formats, including APA.

BE CAREFUL! - In many cases, these auto-generated citations are incorrect.  You still need to check and make sure that the citation is formatted properly.

Books that are written by one or more authors generally follow this format:

Author, A. A. (year book was published). Title of book:

Subtitle of book. Location: Publisher.

Edited books, where each chapter is written by a different author(s), follow this different format:

Author of Chapter, A. A. & Author of Chapter, B. B.

(year book was published). Title of chapter. In A. Editor, B. Editor, & C. Editor (Eds.), Title of book: Subtitle of book (pp. xxx-xxx). Location: Publisher.

For more examples, see section 7.02 of the APA publication manual.

In this example, the entire book was written by a single author. 

In this example, the entire book was written by two authors. 

Edited works are written by a team of people.  Each chapter is usually written by one (sometimes more) people and then all the individual chapters are reviewed and arranged by an editor.  The editor usually writes a something, like an introduction, as well.  That's why you have to cite both the editor AND the chapter author as outlined in this example:

The format for electronic books is exactly the same as the format for print books except you must replace the publisher's location and name with the URL of the publisher's web site.  See section 6.32 of the APA style guide for more information.