Ernest, J. W., & Ashmun, R. D. (1973). Salesmanship Fundamentals (4th ed.). McGraw-Hill.
Dyfyniad Arddull ChicagoErnest, John W., and Richard D. Ashmun. Salesmanship Fundamentals. 4th ed. New York: McGraw-Hill, 1973.
Dyfyniad MLAErnest, John W., and Richard D. Ashmun. Salesmanship Fundamentals. 4th ed. McGraw-Hill, 1973.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.