Datta Gupta, Anupam, and Renuka Visvanathan. “Botulinum Toxin for Foot Dystonia in Patients With Parkinson’s Disease Having Deep Brain Stimulation: A Case Series and a Pilot Study”. Journal of Rehabilitation Medicine, vol. 48, no. 6, Apr. 2016, pp. 559-62, doi:10.2340/16501977-2094.