Here are some Catholic music books for chant. To learn about each one see their descriptions by Jeffery A. Tucker. There are links to download each one.
1. The Graduale Romanum. The book of music for the Catholic Mass, entirely in Latin.2. The Gregorian Missal. All the chants from the Graduale Romanum for Sundays and Feasts, plus English translations with the instructions in English.3. The Parish Book of Chant. A project of the Church Music Association of America. Can be used by beginning choirs so they can get going with all the tunes and words that previous generations took for granted. 4. The Simple English Propers. Reduced English versions of the Gregorian propers for Mass for entrance, offertory, and communion. The Gregorian mode is preserved, and every chant has Psalms. The book was put together by Adam Bartlett.Gregorian Chant Books