Use the Tripod catalog for your home institution to look for all books (print and digital) owned by your college as well as the print titles at the other two schools.
The following subject searches are a sampling of possibilities. To find materials on a topic, try doing a keyword search (called Any Field) in the Tripod Catalog to find some relevant material and then use the subject headings assigned to those titles to find more books.
(capitalis* OR poor OR poverty) AND (religion OR religious OR church*) AND ("latin america*" OR "central america*" OR salvador* OR nicaragua* OR guatemala*) [All Subjects]
"catholic church" mexico history [Subjects]
"liberation theology" [Subject] AND ("latin america*" OR "central america*" OR salvador*) [Subjects]
** Try opening a search above and replace one of the topics with your research interest.
Doctoral students go through an exhaustive literature search when writing their dissertations. They also tend to work on new questions, sometimes ones that have received very little attention from scholars before. You can sometimes obtain these dissertations and benefit from all the bibliographic treasues and new ideas. Check ProQuest Dissertations & Theses to identify dissertations on your topic.