This cache does not require you to enter the library.
Why did the boxer go to the library? To hit the books.
Why did the basketball player go to the library? To read tall tales.
Why did the elf go to the library? To read short stories.
Why did the skeleton go to the library? To bone up for a test.
Why did the cow go to the library? To get 'an udder' book.
Why did the geocacher go to the library? To get a smiley, of course!
After you find the cache, why not step into the library and check out 796.58 for fun.