Doleman, B., Leonardi-Bee, J., Lund, J. N., Heinink, T. P., Bhattacharjee, D., & Williams, J. P. (2018). Pre‐emptive and preventive opioids for postoperative pain in adults undergoing all types of surgery. Cochrane Database of Systematic Reviews, https://doi.org/10.1002/14651858.CD012624.pub2