A5. Christlieb, Don. Pictoral Fingerings for Bassoon. Published by author, 1966, p. 17. 

  / x x | x o x F
Bb B C D

A5. Ewell, Terry B. (09 Feb. 1995). From Gerald Alleva:

 eb    c#
x o o | o o o
   a   Bb
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Heckel-system bassoon fingerings by note name