EENS and Vatican II in relation to the Medievals: https://www.christianbwagner.com/post/the-key-to-understanding-extra-ecclesiam-nulla-salus-and-vatican-ii
Necessity of Explicit Faith: https://www.christianbwagner.com/post/notes-on-implicit-faith-explicit-faith-and-salvation
Necessity of Membership in the Church: https://www.christianbwagner.com/post/outside-the-church-there-is-no-salvation-vatican-i-and-ven-pius-xii

Necessity of the Church from Bl. Pius IX to Ven. Pius XII: https://www.google.com/books/edition/The_Necessity_of_the_Church_for_Salvatio/l2NAAAAAIAAJ?hl=en&gbpv=0