Dictionaries and encyclopedias like the ones listed on this page are a good place to begin your research. They can provide background or general information on a topic, help to narrow a broad topic to a manageable one for your paper, and suggest other sources you might consult for further information.
There are numerous works relating to the history, culture, and religions of Africa in these two collections. Further, you can find chapters focusing on Africa within works on Islam, Christianity, and Judaism.