Organized by category, here is a list of relevant search terms and keywords to guide you like a good witch as you explore the legacy of The Wizard of Oz via Google Scholar (search engine) and MLA International Bibliography (database):
General Keywords
Scholarly Hot Takes
Adaptations:
Historical Context
Visual and Artistic Interpretations
Search features can vary database to database and search engine to search engine, but filters and field searching can be your friend on the yellow brick road in narrowing down your searches as well an orienting your research in a specific year. You can also employ Boolean operators OR to broaden, AND to narrow, and NOT to exclude certain terms/subjects from your search. As seen above, AND seems to be the most effective option for Oz research, but you can use NOT for example when you are specifically seeking The Wizard of Oz book resources NOT film. Boolean operators also work via advanced search in drop down menus like in MLA International Bibliography and typed out in basic searches like on Google Scholar. Quotation marks, as seen above, ensure exact phrase matching!
Regarding Gale Literature as another recommended database, you can explore effectively within “browse topics” or “person search.” For example, under "Children’s Literature" in Browse topics, I clicked “Homosexuality in Children’s Literature” and then added “Oz” as a keyword to search within the results and found a resource titled Over the Rainbow: Queer Children's and Young Adult Literature. Through the "person search", I was also able to find a ton of biographical resources on L. Frank Baum as well as Wicked Author Gregory Maguire. Gale provides literary criticism, biographies, primary sources and literary works, topic and work overviews, reviews and news, and multimedia, enabling you to use them as filters for the research you desire.