He's not in www.findagrave.com which is a generally a great resource for finding where a person was buried.
There are several volunteers in Sonoma County who can help you. One has a county cemetery book and will do lookups and another will look up his obit. You will find the volunteer contact info at www.gengathering.com. You do have to create a user ID and password to enter this web site but access to the volunteer contact info is free.
You can also do a Google search for Sonoma County Cemeteries and then look through the indexed cemeteries. Successful Searching!