Wickboldt, N., Haller, G., Delhumeau, C. and Walder, B. 2015. A low observed-to-expected postoperative mortality ratio in a Swiss high-standard peri-operative care environment – an observational study. Swiss Medical Weekly. 145, 4344 (Oct. 2015), w14205. DOI:https://doi.org/10.4414/smw.2015.14205.