The Trisagion (Greek: Τρισ?γιον "Thrice Holy"), sometimes called by its opening line Agios O Theos or by the Latin Tersanctus, is a standard hymn of the Divine Liturgy in most of the Eastern Orthodox Churches, Oriental Orthodox Churches and Eastern Catholic Churches. In Western Christianity the Sanctus (a different formula) is used in the Mass.

Trisagion /
Trisagion /
Trisagion Prayer – Legion of Mary
The transhuman trisagion
Ypakoe; Depart in Peace; Trisagion; Hadiths
The Trisagion in Isaiah 6:3: an exegetical and theological analysis
Holy Seeds: The Trisagion and the Liturgical Untilling of Time
P.Mon.Epiph. 607: Great Doxology and Trisagion
Liturgia y apocalíptica en Bizancio: Notas sobre la leyenda del Trisagion
MartinezD. G.: P. Michigan XIX. Baptized for Our Sakes: a Leather Trisagion from Egypt (P.Mich. 799). (Beiträge zur Altertumskund...