Code on the side of the books

Hi there! I have figured out some stuff about the code in the side of the books, so I took all the black letters and I'm pretty sure that made an anagram so I am trying to decipher it at the moment, I have found some words; he took rules made near here. I'm trying to find some more combinations and other words, if you can find any please help me out because I would love to know what the code is!
rulhehremadetookenesar are the letters i collectted