Unless you are already familiar with the research topics, you may need an introduction: subject encyclopedias can provide that.
Below are 2 databases of online encyclopedias. In addition, there are a few subject encyclopedias you could look in ...
Start with one of these online collections of reference books. each contains multiple reference books covering diverse topics.
Use the databases above and individual online encyclopedias to explore your field. For example, if you're in public relations, look for ideas in the Encyclopedia of Public Relations linked to below.