M. G. Perroca, M. de C. Jericó, and S. D. Facundin, “Monitoring cancellations of surgical procedures: an indicator of organizational performance”, Rev. Esc. Enferm. USP, vol. 41, no. 1, pp. 113–119, Mar. 2007, doi: 10.1590/S0080-62342007000100015.