Reichheld, F. (2006). The Ultimate Question. HBR Press.
Chicago-čujuhus (17. p.)Reichheld, Fred. The Ultimate Question. Boston: HBR Press, 2006.
MLA-čujuhus (9. p.)Reichheld, Fred. The Ultimate Question. HBR Press, 2006.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.