One search strategy is to browse the shelves in call numbers relevant to your research area. You may do this without realizing it when you get a book after looking it up in the catalog. You can also do this if you do not already have a specific book in mind.
HD 30.3
Communication in organizations
HE 7601 - HE 8700
Telecommunication industry
HF 5410 - HF 5417
Marketing communications
HF 5717 - HF 5735
Business communication
HF 5801 - HF 6182
Advertising
HM 1106 - HM 1171
Interpersonal relations
HM 1206-1220
Sociology: Mass media aspects
KF 2750 - KF 2850
Media law (General - U.S.)
KF 4770
Freedom of Speech laws (U.S.)
P 87 - P 96
Communication & mass media (general)
P 99.5 - P 99.6
Nonverbal communication
PN 1990 - PN 1992.95
Broadcasting
PN 1993 - PN 1999
Motion pictures
PN 4001-4389
Oratory, elocution
R 118-119.95
Health Communication
TR 845 - TR 899
Cinematography
Z 657 - Z 659
Freedom of the press & Censorship