Nothing beats books off a library shelf! Look up/ask your teacher about the more prominent historians for your topics and then read their books! Look how different historians have different ideological views on your historical area. Also, just by reading a historian's perspective, you develop many ideas and themes for arguments in an essay! Above all, enoilgram is right! Understanding a historian's perspective/idea is much more important than the quote itself! Often you can just write for e.g. Historian ____ argues that _________. You don't have to quote!