RT Journal Article SR Electronic T1 Author response to “Lever effect and the optical illusion of safety in laparoscopic cholecystectomy” JF Canadian Journal of Surgery JO CAN J SURG FD Canadian Medical Association SP E243 OP E243 DO 10.1503/cjs.2164209 VO 64 IS 2 A1 Francis Sutherland YR 2021 UL http://canjsurg.ca/content/64/2/E243.3.abstract