Citing E-books follows the same basic rules as citing a book which is printed on paper. With a few exceptions, though. Here you find a few examples of different case.
The citation is similar to that of a paper book:
Lloyd (2005, p. 262) or (Lloyd 2005, p. 262).
In this case the book is an edited one.
Lloyd, CB (ed.) 2005, Growing up global: The changing transitions for adulthood in developing countries, e-book, [E-book]. [Cited 2007-05-05]. Available: http://www.nap.edu/books/11174/html/index.html.
(Smith 2008) or Smith (2008) argues that...
In e-books the page numbers are sometimes unavailable. In those case, use chapter numbers to show where the information comes from.
Smith, A 2008, The Wealth of Nations, Kindle Edition version, [E-book]. Cited 2010-08-10] Amazon.com.
Smith, A 2008, The Wealth of Nations, Adobe Digital Editions version [E-book]. [Citec 2010-08-10] DOI: 10.1036/007142363X.
E-books can be searched in Finna the same way as the paper books. The result list can be modified so that only e-books are shown.
The e-book collections of LUT and Saimaa UAS are somewhat divergent. Use the Finna of your university and login using your username and password to access the e-books availabel for you.
Also search engines like Google Scholar can be used to find e-books.