Before you get started searching through academic journals for sources, it can be helpful to do some background research about your topic. Background research can help you learn about different aspects of your topic or can help you pick a topic if you are still deciding on one. Check out the below resources which provide overviews of various topics.
CRS Reports are produced by the Congressional Research Service, the public policy research arm of Congress and are heavily researched and written by experts in the field on legislative issues. CRS Reports are available fulltext from 1916 to the present.
From the Congressional Research Service homepage:
"The Congressional Research Service (CRS) serves as shared staff to congressional committees and Members of Congress. CRS experts assist at every stage of the legislative process — from the early considerations that precede bill drafting, through committee hearings and floor debate, to the oversight of enacted laws and various agency activities. CRS approaches complex topics from a variety of perspectives and examines all sides of an issue. Staff members analyze current policies and present the impact of proposed policy alternatives."
Note: there might not be a CRS report for every topic - but do try and see if there is!
1. Document Types
Either keep "Select All," or deselect and choose "CRS Reports." You can also add "Topic Pages."
(If you keep "Select All," you will have the opportunity to limit document type within results)
2. Keep the search field to: "All fields except full text"
If you are searching the name of a law: use the "Title" search
3. Enter your keywords. Some examples:
"student loans"
"minimum wage"
school* and (firearm* or gun*)
Reference sources, such as encyclopedias, handbooks, and dictionaries, can also be great background sources! Reference sources will give you an overview of a topic, to make sure you understand the topic before you dive into in-depth sources like journal articles.
Searchinf in UMD Discover, use your keywords and add the defining terms such as:
dictionar*
handbook*
encyclopedia*
biography
bibliographies
bibliography
So, your search would look like this: (notice the capital OR / AND)
("food desert*" OR "food insecurity" OR "food security") AND (encyclopedia* OR handbook* OR dictionar*)
plastic* AND pollution AND (encyclopedia* OR handbook* OR dictionar*)
transgender AND (encyclopedia* OR handbook* OR dictionar*)
Below are some examples of reference books from UMD Discover
Handbook of Research on Environmental and Human Health Impacts of Plastic Pollution by 
Mass Shootings in America: Understanding the Debates, Causes, and Responses by 
Encyclopedia of Food Security and Sustainability by 
