April 28 (Eastern Orthodox liturgics)

• Apostles Jason and Sosipater, of the Seventy, and their companions, at Corfu (1st century):[1] (see also April 29 - Greek)

• Martyrs Saturninus, Jakischolus (Inischolus), Faustianus, Januarius, Marsalius, Euphrasius, Mammius - the holy seven former thieves;
• The virgin Cercyra, and Christodoulos the Ethiopian.

• Martyrs Zeno, Eusebius, Neon, and Vitalis, who were converted by Apostles Jason and Sosipater (c. 63)[1] (see also April 29 - Greek)
• Nine martyrs at Cyzicus (c. 286-299):[1][2][3] (see also April 29 - Slavic)
  • Theognes, Rufus, Antipater, Theostichus, Artemas, Magnus, Theodoulos, Thaumasius, and Philemon
• Martyrs Dada, Maximus, and Quintilian at Dorostolum (286)[1][4] (see also: April 13, August 2)
• Martyr Tibald of Pannonia (304)[1][4][5]
• Saint Auxibius II, Bishop of Soli, Cyprus (4th century)[1][2][6][note 2]
• Venerable Memnon the Wonderworker (6th century)[2][9] (see also April 29 - Slavic)

• Martyrs Aphrodisius, Caralippus, Agapius, and Eusebius (65)[10][11][note 3] (see also May 30 - Greek)
• Saint Mark of Galilee, bishop and martyr (92)[10][note 4][note 5]
• Saint Artemius (Arthemius), Bishop of Sens (609)[10]
• Saint Gerard the Pilgrim (c. 639)[10][13][note 6]
• Venerable Crónán, abbot of Roscrea, Ireland (640)[1][4][10][14][15]
• Saint Pamphilus, Bishop of Sulmona and Corfinium (c. 700)[10]
• Saint Prudentius, Bishop of Tarazona in Aragon (c. 700)[10][16]
• Saint Adalbero, Bishop of Augsburg (909)[10]

• Saint Cyril of Turov, Bishop (1183)[1][17]
• Saint Cyril, founder of Syrinsk Monastery, Karelia (1402)[1]
• Venerable Cyriacus, abbot of Kargopol, Vologda (1462)[4]

• The Miracle at Carthage (c. 610-641)[19][20]
• Repose of Archimandrite Hilarion (Argatu) of Cernica (1999)[1]
• Repose of Hieroschemamonk Dionysius (Ignat) of Kolitsou Skete, Mt. Athos (2004)[1]

• 
  The Nine martyrs of Cyzicus.
• 
  St. Aphrodisius.
• 
  St. Adalbero, Bishop of Augsburg.
• 
  St. Cyril of Turov.
• 
  The Order of St. Cyril of Turov, 2nd degree.

• April 28/May 11. Orthodox Calendar (Pravoslavie.ru).
• May 11 / April 28. Holy Trinity Russian Orthodox Church (A parish of the Patriarchate of Moscow).
• April 28. 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. 119–120.
• Rev. Richard Stanton. A Menology of England and Wales, or, Brief Memorials of the Ancient British and English Saints Arranged According to the Calendar, Together with the Martyrs of the 16th and 17th Centuries. London: Burns & Oates, 1892. pp. 184–185.

Greek Sources

• Great Synaxaristes: (in Greek) 28 Απριλίου. Μέγας Συναξαριστής.
• (in Greek) Συναξαριστής. 28 Απριλίου. Ecclesia.gr. (H Εκκλησία της Ελλάδος).

Russian Sources

• (in Russian) 11 мая (28 апреля). Православная Энциклопедия под редакцией Патриарха Московского и всея Руси Кирилла (электронная версия). (Orthodox Encyclopedia - Pravenc.ru).
• (in Russian) 28 апреля (ст.ст.) 11 мая 2013 (нов. ст.) Archived 2013-12-25 at the Wayback Machine. Русская Православная Церковь Отдел внешних церковных связей. (DECR).