The UC Davis General Catalog is a heavy paperback that outlines pretty much every class and every major offered at UC Davis. The book is given to Freshmen, or you could buy it from the bookstore, but it is available in PDF and HTML form on the Registrar's website. If you have a question regarding your college and graduation, reading this catalog can answer many questions because advisors will generally refer to this catalog to answer things they are unsure of. This includes loopholes and restrictions such as unit requirements.
While the General Catalog is useful to gain familiarity with the courses offered in your major, when registering for your courses you may find the Open Course List to be rather helpful.