The final part of the book contains an analysis of the content of the reform, consisting of a comparative study of the pre- and post-Nikonian editions of the Sluzhebnik (Euchologion). Particular attention is focused on the text and rubrics of the Byzantine Liturgy of John Chrysostom, which underwent the most significant changes. This comparative study confirms the fact that the reform was conducted on the basis of contemporary editions, and not of ancient sources.