How do I cite a book chapter written by the same person who wrote the book?
Answer
In APA, citing book chapters refers to a specific type of book, what we would call an edited book. In this case, there are multiple chapters written by different authors with an overall editor or editors for the book. Your citation then must reflect the name of the chapter author, the chapter name, the book editor, and the title of the book.
With the information you provided in your question, it sounds as if there is just a single author to the book - no other authors writing chapters and no editor.
Therefore you would cite it as a book and not concern yourself with the chapters. An example of citing a book can be found here - http://libguides.css.edu/c.php?g=41681&p=265012
I can find no example in the Publication Manual of the American Psychological Association, 6th edition that shows an example of citing a chapter that is not in an edited book.
However, one of my colleagues has created an example for citing a book chapter from a non-edited book.
Mehrotra, C. M., & Wagner, L. S. (2009). Informal and formal care for older persons. In Aging and diversity: An active learning experience (2nd ed., pp. 205-252). New York, NY: Routledge.
It makes sense. It is the same format as the edited chapter book, but the editor info is left out because there is no editor.
I am not your professor so will not be sitting in judgement of your citation. I think either version meets the "spirit of the law" - allowing your reader to know what your source was and easily retrieve it if need be.