1. Becker, R. A.; Chambers, J. A.; Wilks, A. R. (1988) The New S Language. Pacific Grove, Calif., USA, Wadsworth;.
2. Bock, H. H. (1974) Automatische Klassifikation. Göttingen: Vandenhoek und Ruprecht; (Studia Mathematica).
3. Brown, J.C., Houthakker, H.S. & Prais, S.J. (1953) Electronic Computation in Economic Statistics, JASA, 43, 411–428.
4. Clogg, C.C. (1992), The Impact of Sociological Methodology on Statistical Methodology, Statistical Sciences, 7, 183–207.
5. Comrie, J.L.; Hey, G.B. & Hudson, H. G. (1937) Application of Hollerithequipment to an agricultural investigation. J.Roy.Statist.Soc.Suppl. 4: 210–224.