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