I don’t have access to the published article, but
this article from the Journal of Hospital Infection is one that has been referenced repeatedly by experts over the last few days. 9 days is the top end of the length of time that coronavirus survives on surfaces, according to the abstract. I’ve read and heard interviews from experts referencing this article who have said in most cases it would be a less time, but as yet I have not heard any specifics regarding surfaces and temperature/humidity conditions typically found in libraries.