Piano,Trombone - Level 4 - Digital Download SKU: A0.931494 Composed by Lazaros Delidemos. Romantic Period,Standards,World. Score and part. 2 pages. Lazaros Delidemos #5302867. Published by Lazaros Delidemos (A0.931494). I wrote this short canon for the graduation recital of one of my students whose name is Gregory. So I named the piece (which is a 2part canon with a free accompaniment) GREGORIAN CANON.