The notation Old Style or (OS) is sometimes used to indicate a date in the 'Julian Calendar' (which is used by churches on the "Old Calendar"). The notation New Style or (NS), indicates a date in the Revised Julian calendar (which is used by churches on the "New Calendar").
"In Persia, in the time of king Sapor, the birthday of St. Sadoth, bishop, and one hundred and twenty-eight others, who refused to adore the sun, and by a cruel death purchased for themselves bright crowns."[3]
Kontakion. Second Tone. "With songs let us crown him who was dedicated to the Lord from infancy, and who from his swaddling bands received grace from God, even Leo, the luminary and defender of the Church; for he is her support."[16]
Born in Tournai in Belgium, he became bishop there in 486 and enlightened the pagan Franks who had settled nearby. He died from wounds inflicted by Arian heretics.
One of the three daughters of St Ermenburgh of Minster-in-Thanet in England. She succeeded her mother as Abbess of Thanet. Her relics were enshrined in Canterbury and part of them survive. Her life describes her as 'ever merciful, of easy temper and tranquil'.
Born in Orleans in France, he became a monk at Jumièges near Rouen in about 714. In 721 he became Bishop of Orleans, opposing the theft of church lands by Charles Martel. For this he was exiled to Cologne in Germany in 737. Here he became very popular and so was sent to Liège in Belgium. He spent the rest of his life at the monastery of St Trond near Maastricht in the Netherlands.
The Roman Martyrology. Transl. by the Archbishop of Baltimore. Last Edition, According to the Copy Printed at Rome in 1914. Revised Edition, with the Imprimatur of His Eminence Cardinal Gibbons. Baltimore: John Murphy Company, 1916. pp.53-54.
Rev. Sabine Baring-Gould (M.A.). "S. Olcan, B. of Derkan. (About 500.)." In: The Lives of the Saints. Volume the Second: February. London: John C. Nimmo, 1897. pp.349-350.
Rev. Sabine Baring-Gould (M.A.). "S. Eleutherius of Tournai, B. M. (A.D. 531.)." In: The Lives of the Saints. Volume the Second: February. London: John C. Nimmo, 1897. pp.350-353.
Rev. Sabine Baring-Gould (M.A.). "S. Mildred, V. Abss. (End of 7th Cent.)." In: The Lives of the Saints. Volume the Second: February. London: John C. Nimmo, 1897. p.354.
The Autonomous Orthodox Metropolia of Western Europe and the Americas. St. Hilarion Calendar of Saints for the year of our Lord 2004. St. Hilarion Press (Austin, TX). p.16.
February 20. Latin Saints of the Orthodox Patriarchate of Rome.
The Roman Martyrology. Transl. by the Archbishop of Baltimore. Last Edition, According to the Copy Printed at Rome in 1914. Revised Edition, with the Imprimatur of His Eminence Cardinal Gibbons. Baltimore: John Murphy Company, 1916. pp.53-54.
(in Greek) Συναξαριστής. 20 Φεβρουαρίου. Ecclesia.gr. (H Εκκλησια τησ Ελλαδοσ).
Russian Sources
(in Russian)5 марта (20 февраля). Православная Энциклопедия под редакцией Патриарха Московского и всея Руси Кирилла (электронная версия). (Orthodox Encyclopedia - Pravenc.ru).