1. Measuring Health: A Guide to Rating Scales and Questionnaires;McDowell,1987
2. Validation of and interval scaling: the sickness impact profile;Carter;Health Services Res,1976
3. Psychometric Theory;Nunnally,1978
4. Do rating scales produce biased preference weights for a health index?;Kaplan;Med Care,1983
5. Value preferences for health: meaning, measurement and use in program evaluation;Lipscomb,1982