Getting the right contact info for property owner/seller

Hello. I just started learning about REI last week and I've decided to do it. Lots to learn.

I'm in Los Angeles County, CA.

Let's say I see a property I would like to buy or wholesale. How do I get the correct address for a property owner so I can send a yellow letter? Can I find this online? I don't want to send letters to the renter.

Also, do the lists from listsource.com give you the HOME address of a rental property owner? Or just the actual property address?

Thanks!