The best place to look would be the Library Catalog. Use the search terms < mexico history > . Look at the blue box on the right-hand side of your results page, and select Wentworth to restrict your results to Wentworth library.. Also select E-books, if you only want electronic sources. To open e-books, click on the title of the e-book, then select the Wentworth link at the bottom of the page.
For general reference sources, click on the "Search by Subject" box above the Library Catalog search box. Select Reference. You may then search for Mexico in the databases found here.
Another good source is the Mexico page in the Library of Congress Country Studies website.