Note that for tomorrow's Festival, the Day of St. Mary, Mother of our Lord, there is an antiphon and responsory provided on 0-74 under "Common of St. Mary, Mother of Our Lord." The Brotherhood Prayer Book provides even more resources for celebrating the day on page 521: "The Dormition of Saint Mary, the Mother of God" and also on page 534: "Common of the Blessed Virgin Mary." The hymn appointed in BPB is here sung by Pastor Mayes:
The God Whom Earth and Sea and Sky
Here's an attempt at recording the responsory from Treasury.