Tiešais mārketings
Mārketinga rokasgrāmata- bez nepamatotiem izpušķojumiem. Footnotes ^ Doyle, P. (1998). Marketing Management and Strategy.2nd ed. London: Prentice Hall Europe. P. 276–278
- McGraw-Hill. P. 350–355. ^ Futrell, C. (1990). Fundamentals of Selling. 3rd ed. Homewood, IL: Richard D. P. 217–260. ^ Vechten, L.R.V
- . (1999). Successful Sales Managers Guide to Telephone Sales. Washington, USA: Briggsbooks. 305 p. ^ Penoyer, F.L. (1997). Teleselling
- techniques that close the sale. New York: Amacom Books. 174 p. ^ Heller, R. (1998). Selling Successfully. London: Dorling Kindersley. P. 75–81.