Some general search tips for databases, book catalogs and search engines such as Google:
Which is better, a subject search or a keyword search? They are both useful. It is usually easier to start with a keyword search. Once you find an an item, you can check the record to see which subject terms are used. Subject words are linked in the record so all you ned to do is click to find similar items.
Uses natural language. Type a word or phrase. With keyword you can search for simply "dominican republic" or for (dominican republic OR haiti) or for (dominican republic OR haiti) AND language
Requires specific Library of Congress Subject Headings. The words have to be typed in the exact order used by Library of Congress. Cannot use AND , OR or *.
Relevant subject headings for environemental issues: