Books and encyclopedias!
There is reliable, easy-to-find information in print books and encyclopedias in the library.
The majority of these are on the first floor (reference section) under call number ML102.O
The very best options include:
Opera synopsis secret weapon: Sound Recordings!
CDs and vinyl LPs often contain "liner notes"--little booklets that give you the synopsis of an opera along with line-by-line text with translations! Simply search for a recording in IUCAT and ask the front desk to fetch it for you.