Kindle books or books on e-Readers may lack page numbers. If you are going to quote from them, you can refer to the chapter rather than the page number, if it is not available.
Note: You do not include the edition information if it is the first edition.
Format: in text citation
It is clear that there are numerous ways to eat chocolate bars (Surname, Year, Page/Chapter).
Author/editor surname, initials. (Year) Title [online], edition, platform. Place of publication: Publisher [if available]. Available from: website. [Accessed date].
Example: in text citation
It is clear that there are numerous ways to eat chocolate bars (Elphinstone, 2018).
Example: in text quotation
“Always find a space where you can sit in peace and quiet before you enjoy your chocolate bar” (Elphinstone, 2018, chapter 1).
Elphinstone, H. (2018) How to enjoy a chocolate bar in peace [online]. Kindle. London: Chocoholics Anonymous. Available from: Amazon.co.uk [Accessed 14th May 2018].