The following advice is taken from the APA Style website:
Gladwell, M. (2008). Outliers: The story of success [Kindle DX version]. Retrieved from Amazon.com
Cite in text:
To cite in text, either (a) paraphrase, thus avoiding the problem (e.g., "Gladwell, 2008"), or (b) use APA’s guidelines for direct quotations of online material without pagination (see Section 6.05 of the manual). Name the major sections (chapter, section, and paragraph number; abbreviate if titles are long), like you would do if you were citing the Bible or Shakespeare.
One of the author’s main points is that “people don’t rise from nothing”
(Gladwell, 2008, Chapter 1, Section 2, para. 5).
N: 1. Jane Austen, Pride and Prejudice (New York: Penguin Classics, 2007), Kindle.
B: Austen, Jane. Pride and Prejudice. New York: Penguin Classics, 2007. Kindle edition.
Austen, Jane. Pride and Prejudice. New York: Penguin Classics. 2007. Kindle.