To find encyclopedias, start by going to the Libraries One Stop Search. Enter your term of interest, followed by "encyclopedias". Add "ebooks" if you are looking only for online titles. Sample search: sociology encyclopedias ebooks.
Do the same thing to find handbooks. Sample search: juvenile justice handbooks ebooks.
If you try a search and get no results, try synonyms, or try dropping "ebooks" and look for a paper format.