Books on classical song are at these call numbers:
Analysis and interpretation MT 115-121
Bibliographies Ref ML 128 .S3
Song Literature ML 2400-2862
Translations ML 54.6 (Reference and General Stacks)
See also composer's biographies: ML 410
Classical songs (also called "art songs") are primarily in collections at these call numbers:
Use the library catalog to find songs. The best way, particularly for recordings, is to search the song title as a phrase.
If you need the music for songs by major composers like Schubert, Schumann, Brahms, etc., it's often easiest to go to the shelf at M 1620 to see exactly which volume(s) you need.
Find sources for free online scores under the Scores tab above. Some other sites:
Books of song translations are at call number ML 54.6 in Reference and General Stacks. Recordings can also be a good source for translations.
Online:
Provides International Phonetic Alphabet (IPA) transcriptions and literal translations of about 5,000 art songs and 800 opera arias. “IPA Source is designed to assist singers with foreign language diction and communication. Our members can easily find the repertoire they need in our extensive catalog of 15,768 arias, art songs and liturgical texts in Italian, French, German, English, Spanish and Latin. With IPA Source, educators and artists can skip the translating and phonetic work and sing with confidence and accuracy.”