Encyclopedias, Dictionaries and Handbooks are excellent places to start your research as they contain articles that summarize in a few paragraphs what's most important to know about a topic. Look for key concepts, terms, contexts, and the names of people who have done important work on your topic, plus bibliographies to guide your further reading.
Subject Encyclopedias provide subject context to concepts, events, and people. For example - e-commerce will have different overview in an IT encyclopedia versus a Retail Management encyclopedia.
Subject Dictionaries - these provide a definition of terms, and specialized dictionaries define industry jargon.
Subject Handbooks - Useful for proving ready reference and/or instruction (think manual) on a specific occupation or on a specific aspect of a discipline. Most business e-handbooks are in Books 24x7