What if a patron wants to find books on a certain subject?

Library of Congress Classification System: P

P     Language and Literature (Level 3)

P: Philology, Linguistics

PA; Greek and Latin languages and literatures

PB: Modern languages (General), Celtic languages

PC: Romance languages

PD: Germanic languages (General). Scandinavian languages

PE: English language

PF: West Germanic languages

PG: Slavic, Baltic, Albanian languages and literature

PH: Finno-Ugric, Basque languages and literatures

PJ: Oriental languages and literatures (General), Semitic languages and literatures

PH: Indo-Iranian languages and literatures

PL: Languages and literatures of Eastern Asia, Africa, Oceania

PM: Hyperborean, Indian and Artificial languages

PN: Literature (General)

PQ: French, Italian, Spanish and Portuguese literatures

PR: English literature

PS: American literature

PT: Germanic literature

PZ: Juvenile belles lettres