Extension repertoire by chanting masters of Fyodor Krest'anin ‘s school at the turn of the XVI—XVII centuries

Based on written sources, the authors first consider the problem of extension repertoire by Tsar's singing clerks (“dyaks”) under the direction of outstanding master Fyodor Krest'anin and his unnamed assistant. The manuscripts, which are determined in the scientific literature as Tsar's court singing clerks (“dyaks”) «drafts», made in consequence of some kind of «correction» chant books, are characterized as materials used in the learning process.