E-books are available in various formats (e.g. HTML, Epub, Adobe Digital Editions) and can be read on a variety of devices (PCs, cell phones, e-readers like Kindle, Nook, to name a few).
Lewis, C. S. (2009). Mere Christianity [Kindle edition]. Retrieved from Amazon.com.
“The only things we can keep are things we freely give to God. What we try to keep for ourselves is just what we are sure to lose.” (Lewis, 2009, p. 213).
When an e-book is accessed from an online library like E-book Central, Bentham Science, Dawson, Springer eBook Collection, etc. give the following elements in the entry of the reference list: author(s), date, title of the book, DOI or stable internet address.
Pridmore, S. (2010). Suicide and predicament: Life is a predicament. Bentham eBooks. http://www.eurekaselect.com/node/53816/suicide-and-predicament-life-is-a-predicamentText reference:
Long, M. (2015). Second language acquisition and task-based language teaching. Wiley. http://site.ebrary.com/lib/northwu/Doc?id=10902333Text reference:
Chen, C. W. S., & Sun, Y.-W. (2018). Bayesian forecasting for tail risk. In V. Kreinovich, S. Sriboonchitta, & N. Chakpitak (Eds)., Predictive econometrics (pp. 122-145). Springer. http://link.springer.com/10.1007/978-3-319-70942-0
(Chen & Sun, 2018).