From the Bassoon-Family Fingering Companion by Terry B. Ewell: Cooper, L. Hugh. The Double Reed 1/3 (December 1978): 31. For pianissimo slur from D3 to D4. For D3 L. H.: thumb D, C, B, and Bb keys; cover E and D holes; Db key. R. H.: thumb E key. For D4: L. H.: thumb D, C, B, and Bb keys; cover E and D holes; Db key. R. H.: nothing.