Jenkinson, C., Clarke, C., Gray, R., Hewitson, P., Ives, N., Morley, D., …Williams, A. (2015). Comparing results from long and short form versions of the Parkinson's disease questionnaire in a longitudinal study. Parkinsonism and Related Disorders, 21(11), 1312-1316. https://doi.org/10.1016/j.parkreldis.2015.09.008