California "Registers" Micrographics KFC 35 .A2 1945-current (Cabinets 22-23).
The UMI Comprehensive Index (Comprehensive Index, California Code of Regulations) KFC35 .A24 - Micrographics Room
may be useful for finding the changes to a particular section from 1981 to 1999 (ceased).
The California Regulatory Notice Register (Z Register) Online from the Office of Administrative Law 2018-current. In Print at the Hastings Law Library KFC 35.A23 4th Floor Stacks [1979 - CURRENT].
This additional weekly publication is published by the State Office of Administrative Law. It includes all proposed regulatory changes within state agencies, as well as disapproval decisions, regulations filed with the Secretary of State, CCR Changes with the Secretary of State (title and section changes), and agency contact information. There is no index, so you will need to scan the table of contents in each issue to check for proposed changes. The current year's publications are kept in a white binder at the end of the bound volumes.
Barclay's Law Library KFC57.B32 6the Floor Stacks [1990-1996, ceased]
Changes enacted between 1990-1996 are arranged by broad subjects. Listings of related court cases and affected California Code sections are also included.
California Historical Regulations on Westlaw Searchable CCR from 2002-current
Archived CCR Versions on Lexis Current CCR sections are linked to archived versions 2004-2013 (click on "Archived Code Versions").
The Public Records Act (Government Code § 6250 et seq.) sets out procedures for public access to rulemaking files. You can consult the agency or its legal department and request rulemaking files.