Schaffarik in his Geschichte, p. 40 sq.
We abstain here from giving any historical references, as it would swell the volume beyond all due proportion; and historical notices, with the exception of those circumstances in immediate connection with the language, cannot properly be expected. All philological sources have been faithfully mentioned.
See below in the History of the Russian Language, and the so called Improvement of the Bible and church books.
In modern times this view has been defended principally by Russian philologists, the Metropolitan Eugene, Kalajdovitch, etc.