In the AHS data base it is spelled Berkheart but if you go to Pete Harry's site it is spelled 2 different ways. He spells it Berkheart on the photo and if you click on the photo he spells it Burkhart in the description. When Pte lists parentage of other intros with BB in it he spells it Burkhart.
I've always listed it as Burkhart because that is how it was spelled by Pete Harry when I copy/paste the description.