Wendell R. Smith is generally credited with being the first to introduce the concept of market segmentation into the marketing literature in 1956 with the publication of his article, "Product Differentiation and Market Segmentation as Alternative Marketing Strategies." Smith's article makes it clear that he had observed "many examples of segmentation" emerging and to a certain extent saw this as a "natural force" in the market that would "not be denied." As Schwarzkopf points out, Smith was codifying implicit knowledge that had been used in advertising and brand management since at least the 1920s.