McGrath, P.J., Walco, G.A., Turk, D.C., Dworkin, R.H., Brown, M.T., Davidson, K. … Zeltzer, L. (2008). Core outcome domains and measures for pediatric acute and chronic/recurrent pain clinical trials: PedIMMPACT recommendations. J Pain 9(9), 771-783. doi: 10.1016/j.pain.2008.04.007. http://www.sciencedirect.com/science/article/pii/S1526590008005506.