Bourne JE, Sauchelli S, Perry R, Page A, Leary S, England C, Cooper AR. Health benefits of electrically-assisted cycling: a systematic review. Int J Behav Nutr Phy. 2018 Nov 21;15(1):116. doi: 10.1186/s12966-018-0751-8
Ferguson JE3rd, Goyal RK, Raynor MC, Nielsen ME, Pruthi RS, Brown PM, Wallen EM. Cost analysis of robot-assisted laparoscopic versus hand-assisted laparoscopic partial nephrectomy. J Endourol. 2012 Aug;26(8):1030-7.