Stubhaug A, Grimstad J, Breivik H. Lack of analgesic effect of 50 and 100 mg oral tramadol after orthopaedic surgery: a randomized, double‐blind, placebo and standard active drug comparison. Pain 1995;62:111–8. doi:10.1016/0304-3959(95)00056-x .

PubMed ID: PM:7478700