The required elements of a reference are:

For example:

Freire, P. (2018) Pedagogy of the Oppressed. [Kindle edition] 50^th anniversary edition. Translated by Myra Bergman Ramos. With an introduction by Donald Macedo and an afterword by Ira Shor. London: Bloomsbury.

If you include a quotation from an ebook, without page numbers, use the section heading or chapter heading as a guide to locating your quotation. For the example above:

"Black families are being systematically demolished" by the U.S. child welfare system (Roberts, 2002: Kindle location 44).

Occasionally you may not be able to find out the place of publication in which case use s.l. (sine loco: without place). This is increasingly the case where authors have chosen to self-publish their work, for example:

Gill, R. C. (2016) DBT Peer Connections: Dialectical behavior therapy skills training workbook. [Kindle edition] s.l.: CreateSpace.