"Es enseñanza unánime de los Padres que esta cabeza visible es necesaria para establecer y conservar la unidad en la Iglesia"
Catecismo del Concilio de Trento.
Catechism of the Council of Trent
Catechismus romanus.
Donovan, Jeremiah
https://archive.org/details/catechismofcoun00cathuoft/page/94/mode/2up?q=
Catechism of the Council of Trent for parish priests,
issued by order of Pope Pius V
Revs.
McHugh & Callan
https://archive.org/details/catechismofcounc0000cath/page/102/mode/2up
