These are the main place where people advertise their vacancies, this is also where the top property management companies advertise their vacacies.
I would also suggest Craigs list.
I believe in this area they are called "six-packs"
You can take on six people in a residential neighborhood without needing special zoneing. My father was in one for a few months after my mom died. He had early alzehimer/dementia. One person owned the home and there was a couple who staid their and took care of the residents. It worked out pretty good. They had one and two to a room for a maximum of six at a time.
Be sure to check with the City of Long Beach for permit and possible restrictions. Also, you may want to consider parts of Lakewood and Bellflower.
Lakewood / Long Beach Real Estate Buyers Specialist
Direct Buyer Hot Line 562-708-1117 or 714-397-3735
There are serveral rentals available in the 90815 zip code. Please contact me via email and I'll more than happy to help.
Main Street Realtors