Ron Willingham. The inner game of sellling. Free press.
Chicago-čujuhus (17. p.)Ron Willingham. The Inner Game of Sellling. Free press.
MLA-čujuhus (9. p.)Ron Willingham. The Inner Game of Sellling. Free press.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.