Books are shelved in general subject categories using the Library of Congress classification system. You may want to supplement your use of the catalog with browsing shelf areas for your topic. Below is a brief listing of some of the subject locations in the field of nursing.
BF -- Psychology
HQ -- Family; marriage; women; sexuality; children
Q -- Science - General
QD -- Chemistry
QM -- Human Anatomy
QP -- Physiology
QR -- Microbiology
R -- Medicine - General
RA -- Public aspects of medicine
RB -- Pathology
RC -- Internal medicine
RD -- Surgery
RJ -- Pediatrics
RM -- Therapeutics; pharmacology
RT -- Nursing