Most citation manuals (APA, MLA, Chicago) refer back to the Legal Blue Books for citing bills, laws, court cases, etc. Below are examples of what they may look like, always refer back to Using the California Style Manual and the Bluebook for specifics.
Leg. body (Sen. or Assem.) Bill #, (year, session [Reg. Sess. or 1st Ex. Sess.])
AB 28 passed on Sales and Use Tax this year. I found it at: http://www.leginfo.ca.gov/pub/11-12/bill/asm/ab_0001-0050/abx1_28_bill_20110628_enrolled.pdf
Citation looks like:
Assem. Bill 28, 2010-2011 1st Ex. Sess., ch. 7, 2011 Cal. Stat. http://www.leginfo.ca.gov/pub/11-12/bill/asm/ab_0001-0050/abx1_28_bill_20110628_enrolled.pdf
I want to use AB 445 on Community Redevelopment Law but it is still in committee. I found it at http://www.leginfo.ca.gov/pub/11-12/bill/asm/ab_0401-0450/ab_445_bill_20110331_amended_asm_v98.pdf
Citation looks like:
Assem. Bill 445, 2010-2011 Reg. Sess. (Cal. 2011).