Carpenter G.I, Ikegami N., Ljunggren G., Carrillo E., Fries B.E.  1997.  RUG-III and resource allocation: comparing the relationship of direct care time with patient characteristics in five countries. Age & Ageing. 26(Suppl 2):61-5.

Campbell J.C, Ikegami N..  2000.  Long-term care insurance comes to Japan. Health Aff (Millwood). 19(3):26-39.

Ikegami N., Fries B.E, Takagi Y., Ikeda S., Ibe T..  1994.  Applying RUG-III in Japanese long-term care facilities. Gerontologist. 34(5):628-39.

Hughes C.M, Lapane K.L, Mor V., Ikegami N., Jonsson P.V, Ljunggren G., Sgadari A..  2000.  The impact of legislation on psychotropic drug use in nursing homes: a cross-national perspective. Journal of the American Geriatrics Society. 48(8):931-7.