Beckwith Harry. (1997). Selling the invisible: A field guide to modern marketing. Warner Books / Time Warner Company.
Chicago-čujuhus (17. p.)Beckwith Harry. Selling the Invisible: A Field Guide to Modern Marketing. NewYork ,USA: Warner Books / Time Warner Company, 1997.
MLA-čujuhus (9. p.)Beckwith Harry. Selling the Invisible: A Field Guide to Modern Marketing. Warner Books / Time Warner Company, 1997.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.