1. 2. J. Hakansson, Dental care habits, attitudes towards dental health and dental status among 20-60 year old individuals in Sweden (, thesis ). Malmo, Sweden: University of Lund, Faculty of Odontology- 1978 ; 14 -27 .
2. 3. S Lavstedt, C-O Henrikson, A Bolin, and BG. Jonsson, Tandtillstand och behov av tandvard hos en normalpopulation . En longitudinell epidemiologisk studie. Stockholm: Delegationen for social forskning (dsf), Rapport1982 ; 7 .