Bjorkgren M.A, Hakkinen U., Finne-Soveri U.H, Fries B.E.  1999.  Validity and reliability of Resource Utilization Groups (RUG-III) in Finnish long-term care facilities. Scandinavian Journal of Public Health. 27(3):228-34.

Blaum C.S, O'Neill E.F, Clements K.M, Fries B.E, Fiatarone M.A.  1997.  Validity of the minimum data set for assessing nutritional status in nursing home residents. American Journal of Clinical Nutrition. 66(4):787-94.

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.

Martin L., Hirdes J.P, Morris J.N, Montague P., Rabinowitz T., Fries B.E.  2009.  Validating the Mental Health Assessment Protocols (MHAPs) in the Resident Assessment Instrument Mental Health (RAI-MH). Journal of Psychiatric and Mental Health Nursing. 16(7):646-653.

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.