IMSLP policy does not require such an extensive credit line, but I believe it is deserved in this case.
May 10, 2011
New Haven, Conn. — Scholars, artists and other individuals around the world will enjoy free access to online images of millions of objects housed in Yale's museums, archives, and libraries thanks to a new 'Open Access' policy that the University announced today. Yale is the first Ivy League university to make its collections accessible in this fashion, and already more than 250,000 images are available through a newly developed collective catalog.
The goal of the new policy is to make high quality digital images of Yale's vast cultural heritage collections in the public domain openly and freely available.
As works in these collections become digitized, the museums and libraries will make those images that are in the public domain freely accessible. In a departure from established convention, no license will be required for the transmission of the images and no limitations will be imposed on their use. The result is that scholars, artists, students, and citizens the world over will be able to use these collections for study, publication, teaching and inspiration....