E2-F#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.
x x x | x x x F F#-tr D
"Prepare a wedge of wood, cork, plastic or cardboard":
x x x | x x x E-wedged F#-tr
Heckel-System (German) Bassoon Trills and Shakes by Note Names