If your parish is beginning to sing the Ordinary in Latin, the organist and schola director will really appreciate having a copy of the Vatican Kyriale in standard notation in order to learn the traditional Mass settings, and potentially for schola members who are having trouble learning Gregorian notation… It is republished by Preserving Christian Publications, and the original arrangement was done by Achille P. Bragers in 1937. It is very well suited for use to accompany the congregation – a must have!
To learn to sing the Propers of the Mass, the schola will want to start out with something not too difficult. Learning to sing the Latin language is enough of a challenge, so using simplified music will help. The best resource for this purpose is the Fr. Carlos Rossini arrangement. The Church Music Association of America has provided a free PDF copy of this work on their website. The Neumann Press also has spiral or hardbound copies available.
After your schola has mastered Latin chant, and they’re ready to move on to something more difficult, the Liber Usualis is the premier tool for the schola member. It contains the Ordinary and all other Mass parts, prayers and responses, plus the authentic and quite ornate Gregorian Chant used for centuries to chant the Propers for the entire liturgical calendar… The standard notation version is very hard to find, but there is an online version of this gem found at Quilisma Publications. The Liber in Gregorian notation is very easy to find. The PCP company again has this available in a beautiful black leather cover.