143

38. EDMUNDSON, H.P. and WYLLYS, R.E., 'Automatic abstracting and indexing - Survey and recommendations', Communications of the ACM, 4, 226-234 (1961).

39. YU, C.T. and SALTON, G., 'Effective information retrieval using term accuracy', Communications of the ACM, 20, 135-142 (1977).

40. SPARCK JONES, K., Automatic Keyword Classification for Information Retrieval, Butterworths, London (1971).

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