Reference books are particularly useful when you are beginning research on a new topic. They provide a concise overview of a subject or event, and will help you to build a foundational knowledge to support your studies.
In addition, they can guide you to significant authors, theories, theoretical frameworks, and secondary sources.
Canadian dictionary of finance and investment terms (2nd ed)
by
Jerry White, John Downes, Jordan Elliot Goodman
Encyclopedia of business and finance
by
Burton S. Kaliski, editor
The McGraw-Hill dictionary of international trade and finance
by
Carolyn R. Gipson.