|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.