The utility of the Mattis Dementia Rating Scale in Parkinson's disease mild cognitive impairment. - Pirogovsky, Eva; Schiehser, Dawn M.; Litvan, Irene; Obtera, Kristalyn M.; Burke, Mathes M.; Lessig, Stephanie L.; Song, David D.; Liu, Lin; Filoteo, J. Vincent (Parkinsonism & Related Disorders, 2014)