For an entire e-book:
Author, A. A., & Author, B. B. (Year of Publication). Title of work. DOI or Retrieval statement.
For part of an e-book:
Author, A. A., & Author, B. B. (Year of Publication). Title of chapter or entry. In A. Editor & B. Editor (Eds.), Title of work (pp. xx-xx). DOI or Retrieval statement.
Entire e-book (Publication Manual, 7.02.19-20)
Angell, J. R. (1905). Psychology: An introductory study of the structure and function of human consciousness (3rd ed.). Retrieved from http://books.google.com
Schiradi, G. R. (2001). The post-traumatic stress disorder sourcebook: A guide to healing, recovery, and growth. doi:10.1036/0071393722
E-book from a subscription database
Lois, J. (2003). Heroic efforts: The emotional culture of search and rescue volunteers. Retrieved from ebrary database.
Chapter in or section of a republished book, online version
Freud, S. (1953). The method of interpreting dreams: An analysis of a specimen dream. In J. Strachey (Ed. & Trans.), The standard edition of the complete psychological works of Sigmund Freud (Vol. 4, pp. 96-121). Retrieved from http://books.google.com (Original work published 1900)