| Catholic Encyclopedia: Sts. Cyril and Methodius: Also called Constantine and Methodius. Biography of these ninth-century brothers, Apostles of the Slavs. |
| Catholic Online: Sts. Cyril and Methodius: Reflection on their lives. |
| Cyril and Methodius, Missionaries to the Slavs: Outline of their missionary activities. With prayer in traditional and contemporary language. |
| Cyril and Methodius, Saints: Short note on the fathers of Slavonic literature, in the Columbia Encyclopedia. |
| Cyril, Monk, and Methodius B: Illustrated biography of SS. Cyril and Methodius. |
| Grande Munus: Encyclical of Pope Leo XIII, on SS. Cyril and Methodius, promulgated in 1880. |
| Lives of the Saints: SS Cyril and Methodius: From Alban Butler's Lives of the Saints. |
| Slavorum Apostoli: Commemoration of the Eleventh Centenary of the Evangelizing Work of SS. Cyril and Methodius. Encyclical of Pope John Paul II, promulgated in 1985. |
| St. Cyril and St. Methodius: The story of these two brothers, suitable for children. Preformatted line breaks can make this difficult to read. |
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