Daniel Galadza drew my attention to this doctoral dissertation entirely on-line. Written by Jopi Harri at the University of Turku in Finland, and defended only last week, it analyzes St. Petersburg Court chant and its relation to obikhod, Kievan, and other chant-systems among the East-Slavs. I have not read it yet, but just skimming the table of contents I find it looks fascinating and hope to get back to it at some point this semester.
While on this topic of the study of Eastern Christian chant, go here to the International Society for Orthodox Church Music to see a number of recent publications containing the proceedings of international conferences in different aspects pertaining to Eastern church music.
I am, I confess, an unrepentant and unapologetic snob about these matters, finding Galician and Kievan chant more beautiful than just about anything else on this earth. And the best place to experience it lived out--really lived by an amazing community of real people--week in and week out is the great St. Elias parish in Brampton, Ontario. If you are not following their myriad videos on YouTube, you don't know what you are missing. Pace Hans Urs von Balthasar, when the angels attend the throne of God, they do not always sing Bach and Mozart: they often sing like this: