Libertas Ecclesiae

  Saint Hilary of Poitiers, Commentary on the Psalms

Pope Gregory VII

Gratian, Decretum D.25 c.1, D.87 c.7

Libertas ecclesiastica 

Pope Leo I in a letter to Bishop Leo Antolio

2x Decretales of the Corpus iuris canonici

Gregory IX: X 1.6.51 Laymen forbidden Ius eligendi

Boniface VIII, VI 3.23.5 Ecclesiastical Property