April 29 (Eastern Orthodox liturgics) (English Wikipedia)

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. 120-121.
Very Rev. John O'Hanlon. "Article I.—St. Diochu, or Dichus, of Sabhall, or Saul, County of Down. [Fifth Century.]." In: Lives of the Irish Saints: With Special Festivals, and the Commemorations of Holy Persons. VOL. IV. Dublin, 1875. pp. 537-540.
Very Rev. John O'Hanlon. "Article VIII.—St. Senan, Confessor, in North Wales. [Seventh Century.]." In: Lives of the Irish Saints: With Special Festivals, and the Commemorations of Holy Persons. VOL. IV. Dublin, 1875. pp. 546-547.
Rev. Sabine Baring-Gould (M.A.). "S. Senan, C. (7th Cent.)" In: The Lives of the Saints. Volume the Fourth: April. London: John C. Nimmo, 1897. p. 364.
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. 185-186.

christopherklitou.com

Rev. Oeconomos Christopher Klitou. Feasts and Saints 29th April. The Orthodox Pages.

ecclesia.gr

(in Greek) 29 Απριλίου. Ecclesia.gr. (H Εκκλησία της Ελλάδος).

holytrinityorthodox.com

May 12 / April 29 (Church Calendar). Holy Trinity Russian Orthodox Church (A parish of the Patriarchate of Moscow).

oca.org

Venerable Memnon the Wonderworker. OCA - Lives of the Saints.
Martyrs Diodorus and Rhodopianus—Deacons, at Aphrodisia in Anatolia. OCA - Lives of the Saints.
Nine Martyrs at Cyzicus: Theognes, Rufus, Antipater, Theostichus, Artemas, Magnus, Theodotus, Thaumasius, and Philemon. OCA - Lives of the Saints.
Saint Endellion, recluse of Cornwall. OCA - Lives of the Saints.
Saint Basil, Bishop of Zakholmsk in Montenegro, Serbia. OCA - Lives of the Saints.
Martyrs of Lazeti. OCA - Lives of the Saints.
Venerable Nectarius of Optina. OCA - Lives of the Saints.

orthochristian.com

April 28/May 11. Orthodox Calendar (Pravoslavie.ru).
SERBIAN CHURCH CANONIZES THREE MARTYRS. Orthodox Christianity. May 11, 2018.

orthodoxengland.org.uk

April 29. Latin Saints of the Orthodox Patriarchate of Rome.

synaxarion.gr

Great Synaxaristes: (in Greek) Οἱ Ἅγιοι Ἰάσονας καὶ Σωσίπατρος οἱ Ἀπόστολοι. Μέγας Συναξαριστής.
Great Synaxaristes: (in Greek) Οἱ Ἅγιοι Ἰακισχόλος, Ἰανουάριος, Εὐφράσιος, Μάμμινος, Μαρσάλιος, Σατορνίνος καὶ Φαυστιανὸς οἱ Μάρτυρες πρώην ληστές. Μέγας Συναξαριστής.
Great Synaxaristes: (in Greek) Ἡ Ἁγία Κέρκυρα ἡ Μάρτυς. Μέγας Συναξαριστής.
Great Synaxaristes: (in Greek) Ὁ Ἅγιος Ζήνων ὁ Μάρτυρας. Μέγας Συναξαριστής.
Great Synaxaristes: (in Greek) Ὁ Ἅγιος Νέων ὁ Μάρτυρας. Μέγας Συναξαριστής.
Great Synaxaristes: (in Greek) Οἱ Ἅγιοι Βιτάλιος καὶ Βαλερία οἱ Μάρτυρες. Μέγας Συναξαριστής.
Great Synaxaristes: (in Greek) Οἱ Ἅγιοι Ἀττικὸς καὶ Κυντιανὸς οἱ Μάρτυρες. Μέγας Συναξαριστής.
Great Synaxaristes: (in Greek) Οἱ Ἅγιοι Ἀγάπιος καὶ Σεκουνδίνος οἱ Ἱερομάρτυρες καὶ οἱ σὺν αὐτοῖς μαρτυρήσαντες. Μέγας Συναξαριστής.
Great Synaxaristes: (in Greek) Ὁ Ἅγιος Ἰωάννης ὁ Καλοκτένης Μητροπολίτης Θηβῶν. Μέγας Συναξαριστής.
Great Synaxaristes: (in Greek) Ὁ Ἅγιος Βασίλειος ὁ Θαυματουργός ἐκ Σερβίας. Μέγας Συναξαριστής.