Unless you know the title and/or author of the book you are looking for, research topics should be searched by Keyword to maximize the number of references to a topic.
However, another way to search is to browse by Subject. This strategy is especially useful if you are having trouble narrowing your topic. Books about topics pertaining to anthropology are to be found in the GN section of the Library. Each subclass is further broken down by numbers so as to narrow down by subdiscipline. For example, GR 880 is used for books about folk medicine.
You should bear in mind that Anthropology is an extremely cross-disciplinary, interdisciplinary field of study. Thus, many resources can be found all over the library; for example, linguistic anthropology is to be found in the P section of the library (with other books pertaining to language).