In addition to being perhaps the earliest concept of business strategy to be taught routinely in formal courses, the specific view of strategy formation Andrews taught appears to have provided many of the underlying precepts of what strategy is, for several branches of the strategy literature. The source document of Chamberlain's Theory of Strategy identifies him as "the most influential of the foundational authors of the strategy literature". Although he introduced a number of strategy precepts, Andrews did not set out a detailed concept of what strategy is. Instead he said that he chose to "sidestep the problem of drawing distinctions between objectives, policy and programs of action" Furthermore Andrews did not claim to originate all of the precepts he set out, and it has been noted that some had been introduced previously by Philip Selznick in 1957 or Alfred D. Chandler in 1962.