Do we have any good sources(lecture notes or books) for learning about $Ihara$ Coefficient?


Is there any relation between $Ihara$ Coefficient and the eigenvalues of graphs?


Thanks for any help. 



learning sources about Ihara Coefficient
Following Igor Rivin's suggestion I found the thesis of Matthew Horton (student of Stark and Terras) pretty interesting : ['Ihara zeta functions of irregular graphs'](http://escholarship.org/uc/item/3ws358jm).


