"The whole purpose of any encyclopedia article is to provide a concise overview of generally "established" knowledge on its topic, written for a nonspecialist audience, with a brief bibliography of highly recommended sources for further study (rather than an indiscriminate printout of "everything"). And there are literally thousands of such [specialized] encyclopedias. (Don't be misled by the word "Dictionary" in the title of many of these sets; in library terminology it refers simply to the alphabetical arrangement of articles, not to their length, and so it is frequently used synonymously with "Encyclopedia.")"
Source: The Oxford Guide to Library Research, p. 3-4.
General and subject-specific encyclopedias, dictionaries, and handbooks are a great place to begin your research. Use them to find topic overviews, definitions, facts, and dates and to fill in context on the subject you are studying.
Use the Library of Congress Classification system to find the call number for your subject area. Then, browse the reference shelves in the library to discover encyclopedias, dictionaries, and other authoritative sources on your topic.
Choose the Advanced Search option in OneSearch, WorldCat Discovery or other library catalog. Add the word "encyclopedias" or "dictionaries" as an additional Subject heading to your Keyword or Subject search to find specialized encyclopedias, dictionaries or handbooks on your topic in print and online.
Also try a simple keyword search on your topic with the added word "encyclopedia" to get a larger list of results.