M. Alimohammadi, M. Andersson, and A. Rostedt Punga, “Correlation of Botulinum Toxin Dose with Neurophysiological Parameters of Efficacy and Safety in the Glabellar Muscles: A Double-blind, Placebo-controlled, Randomized Study”, Acta Derm Venereol, vol. 94, no. 1, pp. 32–37, Jul. 2013.