28 That we may pray with greater hope, let us take as our intercessors and protectors of our welfare the Virgin Mary, the great Mother of God, the help of Christians, and protector of the human race; St. Joseph, her chaste spouse, in whose patronage the whole Church greatly trusts; and the Princes of the Apostles, Peter and Paul, the guardians and protectors of the Christian name. Given at St. Peter's in Rome, the twenty-ninth day of June, 1881, the third year of Our pontificate.
Source: Diuturnum (Vatican.va)