No, I cannot. I imagine it's out there somewhere but I'm not going to spend time searching for something that is a basic Catholic principle.
Which, principle is that?
A) The consensus of the theologians that those who fall into public, formal, manifest heresy lose their membership status in the Church?
Or,
B) Your non-sourced opinion that, "Once a member always a member."?
It seems the disagreement is mainly over how someone who was a heretic could "rejoin" the Church.
If someone can go back and forth a million times from being a dead to living member of the Church...then why do you not understand that someone can lose and regain membership status due to loss faith - even while the baptismal character remains?
Faith is the virtue that unites someone to the Mystical Body, without it, they cannot be joined to Her, a public, formal, manifest heretic is ruled to be outside the Church due to their lack of faith - as exhibited by their unwillingness to be corrected by the Church authorities.
Follow the consensus of the theologians on this...
Or,
Stubborn..
I am starting to see why the name fits...