Martinez-Martin, P. ., Schapira, A. ., Stocchi, F. ., Sethi, K. ., Odin, P. ., MacPhee, G. ., … Chaudhuri, K. . (2007). Prevalence of nonmotor symptoms in Parkinson’s disease in an international setting; study using nonmotor symptoms questionnaire in 545 patients. Movement Disorders : Official Journal of the Movement Disorder Society, 22(11), 1623-9. https://doi.org/10.1002/mds.21586 (Original work published 2007)

Evans, A. ., Okai, D. ., Weintraub, D. ., Lim, S. ., O’Sullivan, S. ., , … Review, C. M. of the I. P. and M. D. S. R. S. (2019). Scales to assess impulsive and compulsive behaviors in Parkinson’s disease: Critique and recommendations. Movement Disorders : Official Journal of the Movement Disorder Society, 34(6), 791-798. https://doi.org/10.1002/mds.27689