May 13 (Eastern Orthodox liturgics)
May 12 - Eastern Orthodox Church calendar - May 14
All fixed commemorations below celebrated on May 26 by Orthodox Churches on the Old Calendar.
For May 13th, Orthodox Churches on the Old Calendar commemorate the Saints listed on April 30.
St. Glyceria.
St. George the Hagiorite.
St. Servatius, Bishop of Tongres.
Greek Sources
Russian Sources
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Wikipedia