- The Web Site of The Holy See.
- The Holy See Press Office.
- L’Osservatore Romano.
- Radio Vatican News.
- The College of Cardinals.
- Papal Encyclicals and Other Official Papal Writings
- Popes in the 20th Century.
The Roman Catholic Church in the United States:
The Eastern Rites in the United States:
Official Roman Catholic Documents:
- Catechism of the Catholic Church
- Baltimore Catechism for All Lay Catholics.
- Nazareth Master Catechism:
Parallel Presentation of Aquinas’s Summa with the Trent, Baltimore, St. Pius X, and John Paul II Catechisms.