Check to see if your VitalSource eBook has a DOI. DOI's may be found on the eBook's copyright page. DOI's are hyperlinks (see below).
To find the Copyright page in your VitalSource eBook, go to the Table of Contents > Front Matter > Copyright Page.
DOIs are hyperlinks (ie. beginning with http:// or https://) ex.: http://doi.org/10.1007/s10551-012-1332-4
Place the DOI after the publisher's name in the reference.
No DOI Pattern:
Author, A. A.,& Author, B. B. (year). Title of book. Publisher.
Author, A. A.,& Author, B. B. (year). Title of book. Publisher. http://doi.org/10.1007/s10551-012-1332-4