Ymni_isodion_ths_theotoku_me_thn_tessarakontame...

: Incorporating the daily commemoration of saints alongside the pre-feast hymns of the Nativity.

The phrase refers to the Hymns of the Entrance of the Theotokos (Isodia tes Theotokou) combined with the Tessarakontameron (the 40-day Christmas Lent period or "Sarantaleitourgo") in the Greek Orthodox tradition. ymni_isodion_ths_theotoku_me_thn_tessarakontame...

: Starting on November 21, the choir or chanter transitions from the standard hymns to the beautiful Christmas melodies during the Orthros (Matins) service. : Incorporating the daily commemoration of saints alongside

: The primary hymn for November 21st is: : The primary hymn for November 21st is:

In the Orthodox liturgical calendar, the Feast of the Entrance of the Theotokos (November 21st) serves as the "threshold" for the Christmas season. It is on this day that the Church begins singing the Katavasies of Christmas, "Christ is Born, Give ye Glory!" Guide to the Hymns & Traditions

If you are looking for a specific or PDF booklet with this exact filename for a church choir, these are often found on Greek digital archives like Psaltologion or Analogion.