Gruber-Baldini A.L, Zimmerman S.I, Mortimore E., Magaziner J..  2000.  The validity of the minimum data set in measuring the cognitive impairment of persons admitted to nursing homes. Journal of the American Geriatrics Society. 48(12):1601-6.

Perls T.T, Morris J.N, Ooi W.L, Lipsitz L.A.  1993.  The relationship between age, gender and cognitive performance in the very old: the effect of selective survival. Journal of the American Geriatrics Society. 41(11):1193-201.