Today at Tridentine Latin Mass I heard during the sermon that Pope John XXIII's first encyclical was based on the Most Precious Blood of Our Lord. The priest urged us to read this 'short, profound encyclical'. You may read it here.
The priest's sermon focused exclusively on devotion to the Precious Blood, and I remember after the Consecration of the Precious Blood to offer the prayer, 'be mindful oh Lord of thy creature, whom thou hast redeemed by Thy Precious Blood.'
After the Mass, we recited the litany of the Precious Blood, which the priest had told us during the sermon was the last litany to be officially approved by the Holy See. You may pray the litany here.