Looking for my brother and sister

I am looking for my birth siblings. Before they were adopted, their names were Matthew Bouchard and Christie Butler. I believe they were adopted around 1973 by a college professor at a college in the Los Angeles area (maybe the valley). I believe the adoptive parents were the Williams. Matt would have been about 4 or 5 and Christie would have been 1 or 2. Does anyone have any idea how I might be able to find them?