Crea, Nicola, et al. “APACHE II, POSSUM, and ASA Scores and the Risk of Perioperative Complications in Patients With Colorectal Disease”. Annali Italiani Di Chirurgia, vol. 80, no. 3, May 2009, pp. 177-81, https://annaliitalianidichirurgia.it/index.php/aic/article/view/1528.