1. Lääkintöhallitus, Tautiluokitus 1987, Vol. 1, Valtion Painatuskeskus, Helsinki, 1986 (in Finnish).
2. World Health Organisation, Manual of the International Statistical Classification of Diseases, Injuries and Causes of Death, 9th Edition, Vol. 1, WHO, Geneva, 1977.
3. Statistics Finland, Causes of Death 1995, Helsinki, 1996.
4. H.R. Wulff, P. Schlichting, Manual for Medstat, The Astra Group A/S, Denmark, 1991.
5. M.J. Gardner, D.G. Altman, 1992, Calculating confidence intervals for proportions and their differences, in: M.J. Gardner, D.G. Altman (Eds.), Statistics with Confidence — Confidence Intervals and Statistical Guidelines, Br. Med. J., London, pp. 28–33.