Fries B.E, Nerenz D.R, Falcon S.P, Ashcraft M.L, Lee C.Z.  1990.  A classification system for long-staying psychiatric patients. Medical Care. 28(4):311-23.

Poss J.W, Hirdes J.P, Fries B.E, McKillop I., Chase M..  2008.  Validation of Resource Utilization Groups version III for Home Care (RUG-III/HC): evidence from a Canadian home care jurisdiction. Medical Care. 46(4):380-7.

Cooney, Jr. L.M, Fries B.E.  1985.  Validation and use of resource utilization groups as a case-mix measure for long-term care. Medical Care. 23(2):123-32.

Fries B.E, Cooney, Jr. L.M.  1985.  Resource utilization groups. A patient classification system for long-term care. Medical Care. 23(2):110-22.

Fries B.E, Ljunggren G., Winblad B..  1991.  International comparison of long-term care: the need for resident-level classification. Journal of the American Geriatrics Society. 39(1):10-6.

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.

Fries B.E.  1990.  Comparing case-mix systems for nursing home payment. Health Care Financing Review. 11(4):103-19.