Identify the color-coded elements to cite ebooks in your Reference List:
If no date is specified, put (n.d.) in the year field.
For books or chapters available only online, the URL or DOI takes the place of publisher location and name.
Do not put a period after the URL.
Citations in your paper should be formatted in a black or grayscale font.
See the APA Publication Manual Edition, pages 180-192 for more on the Reference List.