A historical study, the first of its kind at a university level, was done by Father Nicolaj Kostur, currently a priest at the Holy Resurrection Serbian Orthodox Cathedral in Chicago.
The topic is the relations between the Patriarchate of Serbia and the Russian Orthodox Church Outside of Russia between 1920 and 1941.
It was published in English on this site, managed by Deacon Andrei Psarev, Assistant Professor of Russian Church and Canon Law at Holy Trinity Orthodox Seminary (Jordanville, NY) in the United States.
This site is dedicated to the history of the Russian Orthodox Church Outside of Russia. Father Nicolaj Kostur’s study is based on numerous documents, including the ROCOR Synod Archives in New York, and others found at the Stanford University Library and at the State Archive of the Russian Federation (GARF).
Although written in 2005, this study had never been published before. Click here to access it.
Source (with picture of the author)