The Liber Usualis is a book of commonly used Gregorian chant compiled by the monks of the Abbey of Solesmes in France. The Liber was first edited in 1896 by Solesmes abbot Dom Andre Mocquereau (1849–1930). It is currently available from ChantCd.com, a reseller of traditional Catholic books.
This 1,900-page book contains most versions of the ordinary chants for the Mass (Kyrie, Gloria, Credo, Sanctus, and Agnus Dei), as well as the common chants for the Divine Office (daily prayers of the Church) and for every commonly celebrated feast of the Church Year (including more than two hundred pages for Holy Week alone). The "usual book" or "common book" also contains chants for specific liturgical functions - such as baptisms, weddings, funerals, ordinations, and benediction. This modal, monophonic Latin music has been sung in the Catholic Church since at least the sixth century up to the present day.
This Liber Usualis contains an extensive introduction, explaining how to read and interpret the medieval musical notation (square notation of neums or neumes). A complete index makes it easy to find specific pieces.
The Liber Usualis is a must for any choir or schola member wanting to sing the Gregorian Chant of the Traditional Latin Mass. It has the complete Latin chant (in Gregorian Chant notation) for every Mass of the year (Sundays, Solemnities, Commons and Feasts). It also has the complete music for Nuptial Masses, Requiem Masses, Holy Week, and Ordination. It also provides much of the Gregorian Chant to be sung in Latin for the Divine Office (Vespers, Compline, etc.), as well as many other traditional Latin chants and hymns (Litanies, Benediction, etc.) The preface of the Liber Usualis tells the interested choir member how to read and sing Gregorian Chant. This book is a must for any person wanting to sing for the Tridentine Latin Mass.