Ebooks are a terrific source of information, specifically when you are building your basic or foundation knowledge of a subject. Books are generally organized logically and systemically which helps us in learning well about a subject we're not well versed in. Ebooks have all the usual "text features" that print books have including tables of contents, indexes, chapters, page numbers, etc. These "text features" are there to guide us as we navigate the book. Remember that it's not always necessary to read the entire book for your research project; you will frequently be able to read a single chapter to gather the relevant information.
Skim the index from A-Z. Let you eye rest on any word or phrase that seems related to your topic. This might be a direct connection or not. Check the pages to see if the text adds to your knowledge of your topic. Read a bit before and a bit after the exact page(s) listed in the index. Be thorough.