I don't know the exact studies--I was told about them by both my doctor at CCRM and my doctor at Cornell. Although, I feel very confident with the information they gave me. Actually, I am pretty sure my local doctor told me the same thing also b/c this was a big concern of mine.
Instead of Clomid, I would prefer a low dose protocol (estrogen priming/MDL plus 75 menopur per day was mine), but this is definitely more extreme and expensive than clomid.
I don't see any benefit at all of the Clomid Challenge test as you already know your FSH is high and you will require a protocol for poor responders.