Editing Marketing (section)

====Modifications and extensions====

To overcome the deficiencies of the 4P model, some authors have suggested extensions or modifications to the original model. Extensions of the four P's are often included in cases such as services marketing where unique characteristics (i.e. intangibility, perishability, heterogeneity and the inseparability of production and consumption) warrant additional consideration factors. Other extensions include "people", "process", and "physical evidence" and are often applied in the case of [[services marketing]].<ref>Fisk, R.P., Brown, W., and Bitner, M.J., "Tracking the Evolution of Services Marketing Literature", ''Journal of Retailing'', vol. 41 (April), 1993; Booms, B. and Bitner, M.J. "Marketing Strategies and Organizational Structures for Service Firms" in James H. Donnelly and William R. George (eds), ''Marketing of Services'', Chicago: American Marketing Association, 47–51; Rafiq, M. and Ahmed, P.K. "Using the 7Ps as a Generic Marketing mix: An Exploratory Survey of UK and European Marketing Academics", ''Marketing Intelligence & Planning'', Vol. 13, no. 9, pp. 4–15</ref> Other extensions have been found necessary in retail marketing, industrial marketing and internet marketing.