Azarenkov, N., A. Gapon, and S. Dudin. “Heuristic Solution of Langmuir Problem in Arbitrary Domain”. Ukrainian Journal of Physics 62, no. 1 (December 23, 2018): 33. Accessed July 13, 2020. https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2018725.