Fernandez HH, Aarsland D, Fénelon G, Friedman JH, Marsh L, Tröster AI, Poewe W, Rascol O, Sampaio C, Stebbins GT, Goetz CG. Scales to assess psychosis in Parkinson's disease: Critique and recommendations. Mov Disord. 2008 Mar 15; 23(4):484-500.