Huvudgrupp 1

• Gorsuch, R.L., Factor Analysis, 2nd ed., LEA publ., 1983
• Lorig, K, Outcome measures for health education and other health care interventions, SAGE publ., 1996
• Streiner, D.L.; Norman, G.R., Health measurement scales.: A practical guide to their developement and use., 3rd ed., Oxford University Press, 2003