The starting point and center of the work are seven liturgical manuscripts from the Biblioteca Apostolica Vaticana, most of which were created between the mid-13th and early 14th centuries. These are codices specifically intended for Dominican liturgy, including two graduals, four antiphonaries, and a psalter-hymnal, which form a group due to their coherent numbering from the 19th century. The author demonstrates for the first time that the manuscripts likely left the Zurich monastery of St. Katharinental as a result of secularization in the second quarter of the 19th century. Based on the Graduale Vat. lat 10769, the author reconstructs a large group of manuscripts around the five older codices of her group, which she calls the "Zurich Group." The uniformity of the book decoration, the occasional use of painting instructions, and the heterogeneity of the contents are noted.