Fr. Parsch was a very important member of the Liturgical Movement, as was Fr. Jungmann, a Jesuit who published several very good books. Dom Garanger and his multivolume work on the Liturgical year is a wonderful set. There were other greats, Fr. Louis Bouyer, who was a Lutheran Minister who converted to the Catholic Church, Archdale King, a former Anglican Clergyman, who became Catholic and remained a layman. Romano Guardini also wrote and continues to have in print good works on the spiritual aspects of the Mass. As Fr. Freney, who’s book on the Spirituality of the Mass in the Light of Thomistic Theology, is a classic, when you can find it.