Versified Rules (lat. Regulae rhythmicae, beginning of the 11th c.) by Guido of Arezzo is the first textbook on music in Western music history composed completely in verse. It contains all main subjects of the plainchant medieval theory, that is: diatonic scale, division of monochord, classification and properties of consonances, church modes, and some approaches to melodic composition intended for an advanced reader. It is mostly known as a treatise where "our" linear notation was for the first time (along with Prologue to Antiphonary by the same author) theoretically described. This critical Russian translation of the Regulae is based on editions of the original treatise by Joseph Smits van Waesberghe (1985), Dolores Pesce (1999) and Angelo Rusconi (2008), subject to eighth authentic Guidonian manuscripts of the 11th and 12th centuries. Extensive commentary should help better understanding of loci obscuri of the original. Additionally, four annotated color facsimile pages from the Guidonian manuscripts (incl. examples of the authentic "Guidonian" notation) are placed in the Appendix to this book.