In a column for the Boston Pilot, Mary Elizabeth Sperry of the U.S. Conference of Catholic Bishops explained how the saints were included in the Missal:
The saints new to the third edition of the Roman Missal include saints, like St. Augustine Zhao Rong, who were canonized after the second edition of the Roman Missal was published in 1985. Some of these saints, including St. Lawrence Ruiz and St. Andrew Dung-Lac, have been on the U.S. calendar for years. However, the new Missal will be the first time their prayer texts have been available in the printed book. Other added saints appeared on the liturgical calendar until 1969, when the calendar was simplified and many saints' observances were removed. Also restored to the calendar are observances for the Most Holy Name of Jesus and the Most Holy Name of Mary. Still others saints and observances added to the Missal highlight important teachings of the Church such as the teaching on Mary (Our Lady of Fatima) and on the Eucharist as the Sacrament of Christ's love (as promoted by St. Peter Julian Eymard).
See the full list of saints.