C. Keller, A. Paixao, M. A. Moraes, E. R. Rabelo, and S. Goldmeier, “Pain scale: implementation for patients in the immediate postoperative period of cardiac surgery”, Rev. Esc. Enferm. USP, vol. 47, no. 3, pp. 621–625, Jun. 2013, doi: 10.1590/reeusp.v47i3.78003.