- Stefano, Simone di1
- Strozzi, Giovanni1
- Strozzi, Niccolò1
- Summa theologica (Thomas, Aquinas, Saint)1
- Sveti Nikola (Abbey : Šibenik, Croatia)1
- Switzerland--Lucerne1
- Switzerland--Monthey1
- Synonyms1
- Tables1
- Tavener, William, active 14501
- Taviani, Alamanno1
- Taxation, Papal1
- Testamentum (Francis, of Assisi, Saint)1
- The Great Western Schism (1378-1417)1
- Theology, Doctrinal--Middle Ages1
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- Theology--Study and teaching--Catholic Church1
- Thilla, Berto1
- Third Order Secular of St. Francis1
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