Need help finding original birth cert

Can someone out there help me find my husband's original birth certificate?He was born in Los Angeles, California in 1939.His birth father died when he was 2 and his mother remarried when he was 8.His stepdad adopted him to make things easier name-wise in school.But the state sealed his original certificate and refuses to unseal it...even though his adoption is hardly a shock to him!He very much wants to know about his birth father.His mother died years ago and no one else remembers anything.If you have a suggestion, I would very much appreciate it.Thanks.