Subject Headings allow you to find relevant material grouped together including titles that do not use the keywords you may have been searching.
Finding subject headings
Look at a book record in Tripod, check the subjects assigned to it, and choose whatever ones are relevant for your research.
Example: Reconciliation, Nations and Churches in Latin America, edited by Iain S. MacLean. Ashgate Press, 2006
Subjects:
Subject search church and state latin america =47 targeted results
Refining subject searches
You can combine different concepts into a single subject search for precision. The results are more focused than a keyword search.
But all the words have to be terminology used in library subject cataloging.
To ensure this, you can use subject headings you have already found. Another option is to browse in the subject headings for more choices.
Combination subject search: