The publication gives a detailed overview over the eighteen liturgical manuscripts of the "Supplementum graecum" at the Austrian National Library. These manuscripts are of great interest for the research of music in general as they date from 12th to the 19th centuries. They contain a great variety of notational practices, musical traditions, genres and composers. With the help of these manuscripts not only the evolution of music liturgical books can be reconstructed but also the compositional styles and the various stages of development of the different notations until the reform of 1814 can be traced. The first part of the book contains the overview over the individual manuscripts, their structure and their repertoire, whereas the second part is dedicated to the composers and their biographical details. The third and central part of the book brings analyses of selected genres, such as the "Anastasimatarion", the eleven "Heothina" and the "Cherubika". A special chapter deals with the so-called "Papadike" - a sort of short introduction to Byzantine notation, which can be found at the beginning of most of the manuscripts. The publication also includes a detailed register of the more than 1600 chants and their composers, as well as colour plates of parts of the manuscripts.