First thing is to write down what keywords including synonyms you know that describe your topic.
ex 1. Ebooks, E-books, electronic books, digital libraries
ex. 2. E-rate, Telecommunications Act of 1996
Look at your topic from BROADER, NARROWER, and RELATED point of view.
example 1: topic is e-rate
BROADER: digital divide, internet in schools (or libraries)
RELATED: filtering internet
example 2: topic is e-books in libraries
BROADER: digital information, internet, book industry
NARROWER: E-book pricing, e-book licensing
RELATED: online textbooks, publisher bundled collections, leasing versus ownership, first-sale doctrine