C#2-D#2. Christlieb, Don. Pictoral Fingerings for Bassoon. Published by author, 1966, p. 19. Timm, Everett LeRoy. The Woodwinds; Performance and Instructional Techniques. Boston: Allyn and Bacon, 1964, p. 171. Cooper p. 5. "Prepare a wedge of wood, cork, plastic or cardboard."
Eb-tr Db-wedged x x x | x x x F E C D
Heckel-System (German) Bassoon Trills and Shakes by Note Names