Five kondakarian manuscripts dating from the 11 to 13 century belong among the oldest witnesses of Russian church music. The Slavonic church texts are accompanied by a peculiar notation which represents the most complex notational system of the European Middle Ages. For centuries this system has been viewed as being undecipherable. In 1962 the author of this book succeeded in deciphering this notation using various methods even though directly compatible Greek sources were unknown at that time. His research appeared in two issues of journal which ceased publication several years ago. After the publication of the first part of this study a Greek philologist discovered in