from google Translate

Rejoice in God
second edition
In 1974, the first edition of the work came to light, entitled "Jubilate Deo", which, in response to the wishes expressed by the Second Vatican Council in the Constitution on the Sacred Liturgy, pursued the goal that the Christian faithful could also sing in Latin the parts of the Ordinary Mass that refer to them at the same time. so that Gregorian chant, "proper to the Roman liturgy" (Sacrosancte Concilium n. 116), joined the eucharistic celebrations of God's people more frequently with its melody, and strongly encouraged them.
Now, however, it seemed appropriate to prepare a second edition, which would provide the songs for the celebration of the Mass, as well as various songs in a larger number, in order to supply a larger collection suitable for different situations.
It is still hoped that by using this instrument, Gregorian chant, a common bond of unity will be found, which will make so many peoples completely one nation, gathered together in the name of Christ with one heart, one mind and one voice.
From the building of the Congregation for Divine Worship, on November 22, 1986, in memory of St. Cecilia, virgin and martyr.
Paulus Augustinus, Card. Mayer, Prefect

perg,

I got my copy from the Vatican Bookstore. You really have to search for it though.