For the next two years, librarians at The University of Pennsylvania will catalogue letters, sheet music, recordings and notebooks of Ray Evans, the lyricist responsible for some of the most popular songs of the 20th century.

Penn has accepted the papers of the American songwriter who graduated from the university in 1936. His songwriting partner, Jay Livingston, graduated from Penn in 1937. Together, they wrote the perennial Christmas classic "Silver Bells."

They worked mostly for Hollywood films, in which some of their best work debuted. They won three Academy Awards for "Que Sera Sera" (1956), "Mona Lisa" (1950), and "Buttons and Bows" (1948). Here's a sample from the latter:

Gimme Eastern trimmin' where women are women

In high silk hose and peek-a-boo clothes

And French perfume that rocks the room

And I'm all yours in buttons and bows.

They did their fair share of television too. The theme music to "Bonanza" was written by Evans and Livingston. Evans' lyrics were ultimately removed from the fiery opening credits, but a young Johnny Cash recorded them:

The claim we hold is as good as gold. Bonanza!

Hand in hand we built this land, the Ponderosa Ranch...

The University of Pennsylvania houses the papers of other important musical figures, such as conductor Eugene Ormandy and opera singer Marian Anderson. The Evans collection, delivered in June, is the University's first of a writer of 20th century popular song.

"The connection with Penn, the importance of Penn serving as that foundation for connecting these two people together, starting them on their career, is something we want to have for others to think about and research," said manuscript curator Nancy Shawcross.

Shawcross says the donation from the Ray & Wyn Ritchie Evans Foundation will result in an exhibition in the spring of 2012. An interactive website planned for 2013.