1. Maslow proposes that human needs exist on a number of levels ranked in order of priority, viz. Physiological, Safety, Belongingness and Love, Esteem and Status, Self-actualisation. Each level of need must be satisfied prior to the one below it in the hierarchy. Abraham H. Maslow, Motivation and Personality (New York: Harper & Row, 1954).
2. Laurence Abbot, Quality and Competition (New York: Columbia University Press, 1955) p. 9.
3. Joan Robinson, The Economics of Imperfect Competition (London: Macmillan, 1932)
4. Edward Chamberlin, The Theory of Monopolistic Competition (Cambridge, Mass.: Harvard University Press, 1933).
5. M. J. Baker, Marketing New Industrial Products (London: Macmillan, 1975).