Boy - that's an open-ended question (which interestingly no one
seems to have responded to yet - what's up with that?)
Your library should definitely start with DAMA's DM-BOK. I think Danette McGilvray's "Executing Data Quality Projects" is not only a great data quality book, but one of the best books on data. Bill Kent: Data and Reality. ISO 704 and ISO 1087 are international standards on "Terminology" that I think are critical to data modelling specifically and enterprise data management more broadly. CMMI's Data Management Maturity Model (DMMM). David Hay's Data Model Patterns. These recommendations are just from memory .... if I looked at my library I'm likely to find more.