Moving back my question to MO References on Gerbes question is migrated from MO to meta. It was never about MO. I was only giving information about search I have done. None of the comments except one has objection with this. None of the answers says anything about MO. I have even taken that users objection and removed information about MO. Can it go back to MO now?

The question on MathOverflow has been restored.

The corresponding question on Meta.MathOverflow has been deleted.