Finding background information in a specialized reference work at the beginning of your research is especially important if you are unfamiliar with the subject area, need to focus or narrow your topic or are not sure from what angle to approach your research.
Specialized dictionaries, encyclopedias, handbooks or even books can provide background information/broad overview on your topic, keywords or concepts that relate to your topic and reference lists that help you find additional resources.
Musculoskeletal, sports, and occupational medicine
by
Micheo, W.
Measurement and evaluation in physical activity applications : exercise science, physical education, coaching, athletic training, and health
by
Philip A. Bishop
The muscle test handbook : functional assessment, myofascial trigger points and meridian relationships
by
Hans Garten