Variations on "A Solis Ortis Cardine", 1973

This appears to be only the first page of a larger piece of music. The note on the bottom of the page says the the following: "The entire piece may be played as a Prelude, etc. Another, more interesting use would be to treat the variations as "versets" inserted between the singing of each stanza of the Plainsong Hymn (SBH #34). On the back side of this manuscript page is a piece entitled, "Agnus Dei," which is a simplified (3-part) organ accompaniment for a chant "Lamb of God." It is unclear at this time which chant Mass this is from.