Looking for siblings removed in early 1970's

I am searching for my 2 siblings who were removed due to abuse/neglect in 1971 or 72.One was a girl and one was a boy. Our birthmom was also adopted.I was told that our parents were married.My birth last name was Martin.I am not sure if that is my siblings last name at adoption though.My email address is John_Betty@mysiouxland.com