Session laws are statutes passed by a legislature, organized by date (i.e. year and then chapter number within the year). California's session laws are variously referred to as Statutes of California, Statutes and Amendments to the Codes, and Statutes and Digests of Measures.
For bills passed before 1993, once you've identified the relevant year and chapter number, your next step is to retrieve the session laws for the relevant year and then browse to the relevant chapter number, to view the text of the statute as it was originally passed.
Additionally, you'll want to check at the beginning and end of the session laws for the relevant year for sections labeled Table of Laws Enacted or Summary Digest. These provide tables that allow you to convert your chapter law number to a bill number, which you will need to retrieve copies of the bill and the bill's history.
For bills passed after 1993, Lexis and Westlaw typically provide the bill number, so you can skip accessing the session laws and proceed directly to retrieving the bill on the legislature's website, which will also include a tab identifying the history of the bill and a tab of bill analyses, dramatically simplifying your research.
The California session laws are readily available online for free:
Copies of the California session laws are available at the library in print:
Before statutes are compiled into the official session laws, they are first published as individual chapter laws and compiled into unofficial session laws published by Lexis and Westlaw, also available at the law library in print: