There are a number of strategies to build a secondary reading list, but keep in mind that doing this effectively takes time. One common starting place is to go to the bibliographies and footnotes of related books and dissertations. This is a tried and true way to build a list, and can often save you time.
Reference resources are another great way to find relevant secondary material. These include bibliographic databases and databases of encyclopedia articles with suggested reading lists. There are many reference databases -- here are a few to consider starting with:
Subject indexes, some of which provide full-text access to articles, are major resources for finding scholarly articles. Two subject indexes that are central to getting started are:
Beyond these two indexes, there are many more subject indexes, such as:
Another effective way to find secondary sources is through the library catalog (Orbis or Books+). Once you find a book that is relevant to your topic, click on the "Subject" links at the bottom of the record, which will take you to additional items that have been assigned the same subjects. Also, you can copy and paste these subject terms into new searches, as they can help you gather keywords that will prove useful to your research.