There are some amazing opera resources available to you, both through the Library, and online. These range from libretti and opera synopses to works that set a historical context, provide stylistic interpretations, or even biographical information about the composer.
And, while all of this may be more than you need for a given performance, it might be just what you need to learn the intricate details of the opera!
Not all of these resources are created equal, though... Some are only available in a foreign language, while others are little more than a paragraph. So, it's important to do a thorough search to see what is available.
Finding Opera Resources
Locating opera resources is very similar to finding sheet music. The major difference is that you will not limit to Musical Scores!
Not finding what you're looking for? Broaden your search to: opera AND Wagner... or opera AND history... It may be that we don't have a book dedicated to a specific opera, but perhaps we have one for that composer, the musical period, or even a broad history!
These are general recommendations for getting started, and you may find useful titles in other parts of the collection (for instance, literature on vocal music is in the range of ML1400-3275).
Depending on the composer, you may find many books about their lives and role in the history of music. Some might cover their whole life, while others focus on a specific period, or even their life while they composed a landmark work.
Finding biographical/historical sources:
BEWARE of online sources not affiliated with a known organization (such as WPU, NPR, Library of Congress, etc.). The information provided may not be entirely accurate or trustworthy.
Some scores will provide detailed information on how to pronounce, emphasize, and interpret the words in an opera or vocal work.
The Library subscribes to an online resource called IPA Source, as well as a number of books dedicated to proper diction in a number of different languages:
As with diction, certain stylistic components of a particular opera or period may be available to assist with staging or performance.
Sometimes, these will be available in the full score, and sometimes you will need to look elsewhere.