1. US Census Bureau, online database. www.census.gov
2. Smith ES, Fleischer AB Jr, Feldman SR (2001) Demographics of aging and skin disease. Clin Geriatr Med 17:631–641
3. Yaar M, Gilchrest BA (2003) Aging of skin. In: Freedberg IM, Eisen AZ, Wolff K, Austen KF, Goldsmith LA, Katz SI (eds) Fitzpatrick’s dermatology in general medicine, vol 2. McGraw-Hill, New York, pp 1386–1398
4. Allsopp RC, Vaziri H, Patterson C, Goldstein S, Younglai EV, Futcher AB, Greider CW, Harley CB (1992) Telomere length predicts replicative capacity of human fibroblasts. Proc Natl Acad Sci U S A 89:10114–10118
5. Wespes E, Schulman CC (2002) Male andropause: myth, reality, and treatment. Int J Impot Res 14Suppl 1:S93–98