To search for APA e-books on PsycNET, check only the "APA books" database as shown below:
To browse APA e-books, click "Browse" at the top of the page and then click Books & Encyclopedia Entries. Here you can browse by year, author, topic, title, or release date.
After locating a title, click on the "TOC: Chapter PDFs" link next to the image of the book.
This will take you to the table of contents for the selected e-book. Click on the desired chapter title to proceed to the chapter's record page, or click "PDF" to download the chapter.