The Seymour Library uses the Library of Congress call number classification system. To browse theatre topics, here are some good places to start:
GV1580-1799.4 Dance
GV 1588 Dance Philosophy (and theory)
GV 1600 Dance criticism, appreciation
GV 1645-1728 Dance history (and historical dance)
NA1-9428 Architecture
NK2200-2750 Furniture
NK4700-4890 Costume
PN1600-3307 Drama (general)
PN1720-1861 Theatre History
PN2061-2071 Acting
PQ500-591 French Drama
PQ4133-4160 Italian Drama
PQ6098.7-6129 Spanish Drama
PR621-744 English Drama
PS330-353 American Drama
PT605-709 German Drama