https://en.wikipedia.org/wiki/Oktoih
Cetinje Octoechos - Wikipedia
cetinjeoctoechoswikipedia
https://www.merriam-webster.com/dictionary/octoechos
OCTOECHOS Definition & Meaning - Merriam-Webster
The meaning of OCTOECHOS is a liturgical book of the Eastern Orthodox Church attributed to St. John of Damascus and containing all hymns to be used at offices...
octoechosdefinitionmeaningmerriamwebster