42. GOFFMAN, W., 'On relevance as a measure', Information Storage and Retrieval, 2, 201-203 (1964).

43. NEGOITA, C.V., 'On the notion of relevance', Kybernetes, 2, 161-165 (1973).

44. GOOD, I.J., 'The decision-theory approach to the evaluation of information retrieval systems', Information Storage and Retrieval, 3, 31-34 (1967).

45. COOPER, M.D., 'A cost model for evaluating information retrieval systems', Journal of the American Society for Information Science, 23, 306-312 (1972).

46. MARSCHAK, J., 'Economics of information systems', Journal of the American Statistical Association, 66, 192-219 (1971).