First off, the death record for Robert Sidney Landing:
Landing, Robert Sidney, b. 18 May 1916, male, b. Colorado, d. Alameda County, CA 28 May 1992, ss#543-14-4721, age 76.
Anyone can obtain a copy of the death certificate.Go to www.vitalrec.com and work your way down to Alameda County.The site describes the $ and info required to order.You can either write to the County of Alameda or use the vitalrec site with a credit card (a few more dollars, but MUCH MUCH faster).I've used them many times and they are a great company (I'm not affiliated with them).
If your Mr. Brewer was adopted, his name would have legally been changed at the time of adoption (via the court in the county where he was adopted).Some county courts maintained the records and sent off copies to the State of California.Most just sent them off to the State of CA.If the county where he was adopted still has the record, he might be able to obtain it from the County.I believe that it requires a court order to obtain the adoption records from the State of CA.They are NOT very helpful and are required to keep confidentiality of records.However, if one of the birth parents registered with the State of Ca and said they wanted their son to know who they were, there may be some record at the State level that he can get ahold of.
I would suggest he write to the County of Alameda for his adoption records (if that's where he thinks he was adopted?)It's certainly worth a try!Also, he should write to the State of California for his records.That address is on the www.vitalrec.com site also.
Also, if looking for family members of his father, you might want to try to obtain the obituary for his father in Alameda County.