A manual for writers of research papers, theses, and dissertations, 7th edition - Kate L. Turabian 2007

Make your topic manageable
Moving from a topic to a question to a working hypothesis
Part I. Research and writing: from planning to production

If you pick a topic whose name sounds like an encyclopedia entry—bridges, birds, masks— you'll find so many sources that you could spend a lifetime reading them. You must carve out of your topic a manageable piece. You can start before you head to the library by limiting your topic to reflect a special interest in it: What is it about, say, masks that made you choose them? What particular aspect of them interests or puzzles you? Think about your topic in a context that you know something about, then add words and phrases to reflect that knowledge:

masks in religious ceremonies

masks as symbols in Hopi religious ceremonies

mudhead masks as symbols of sky spirits in Hopi fertility ceremonies

You might not be able to focus your topic until after you start reading about it. That takes time, so start early (you can do much of this preliminary work online):

Begin with an overview of your topic in a general encyclopedia (in the bibliography, see items in category 2 in the general references); then read about it in a specialized one (see items in category 2 in your field).

Skim a survey of your topic (encyclopedia entries usually cite a few).

Skim subheads under your topic in an annual bibliography in your field (in the bibliography, see items in category 4 in your field). That will also give you a start on a reading list.

Search the Internet for the topic (but be cautious about what you find; see 3.4.3).

Especially useful are topics that spark debate: Fisher claims that Halloween masks reveal children's archetypal fears, but do they? Even if you can't resolve the debate, you can learn how such debates are conducted (for more on this, see 3.1.2).