1. Cummings JL, Benson DF: Dementia: definition, prevalence, classification, and approach to diagnosis; in: Dementia. A Clinical Approach. Stoneham, ButterworthHeinemann, 1992, pp 1-17.
2. Dementia. Age-dependent incidence, prevalence, and mortality in the old old
3. Activities of Daily Living in Patients with Dementia
4. Office of Population Census and Surveys: Classification of occupations and coding index. London, HMSO, 2006.