If you like Wikipedia then you already use reference matieral. What most people like about Wikipedia is how they can get a comprehensive overview of a topic. Most people stop there, but in most cases this is just the starting point of research. Reference material is more than just encyclopedias and dictionaries. They also include biographies of people, almanacs, quotes, and maps. Use these resources as a way to learn more about your topic or to pick other resources that will be more indepth.