These resources contain many reference books (encyclopedias, dictionaries, handbooks, etc.) covering a wide range of subjects.
They are good resources when you aren't sure of your topic; they allow you to explore a topic by providing you with general background information about a subject.
These resources contain many reference books, (such as encyclopedias, dictionaries, handbooks, etc.) covering a wide range of subjects.
They are a good place to begin your research, especially when you aren't sure of your topic; they provide you with general overviews of a particular subject.