Williams B.C, Fries B.E, Mehr D.R.  1996.  Patterns and determinants of health services use and mortality after VA nursing home care. Journal of Aging & Health. 8(2):280-301.

Kiely D.K, Simon S.E, Jones R.N, Morris J.N.  2000.  The protective effect of social engagement on mortality in long-term care. Journal of the American Geriatrics Society. 48(11):1367-72.