This list focuses on databases that emphasize colonialism. There are many other options for primary sources, especially British and American. Please see my British and Irish History Research Guide and United States History Research Guide for those lists, or ask me.
Use the Library Catalog to find books. Be sure to pay attention to the date and publisher of the book - the Catalog does include older materials and primary sources.
Catalog Search results will include everything in the University of Michigan Library physical collection (books, audio, video, maps, musical scores, archival materials, and more), as well as materials available online such as electronic books, streaming audio and video, and online journals.
Use these databases to find articles from scholarly journals. Scholarly journals also have features like book reviews, so make sure it's a research article.