Foley Library owns a large number of muscial scores that can be accesed through PRIMO or the library catalog. To search for scores in PRIMO search by composer or other key word and then limit to score under Resource Type on the left column. In the classic library catalog use the advanced search feature and choose music score the word score as Type.
In 2012 Howard W. Wildin donated his entire collection of American Popular Sheet Music to Gonzaga University. This collection of about 20,000 pieces dating from 1835 to 1980, documents the unique attitudes, tastes, and biases of bygone eras. Many of these pieces have been made available online through the Gonzaga University Digital Collection.
Selected scores are also available through Music Online.
Not sure which encyclopedia or dictionary will have coverage of your topic? Search Reference Universe, a cumulative index to electronic and print reference works at Foley Center Library.