Fischer A, Zimovetz E, Ling C, Esser D, Shoof N. Humanistic and cost burden of systemic sclerosis: a review of the literature. Autoimmun Rev. 2017 Nov;16(11):1147-54. doi: 10.1016/j.autrev.2017.09.010
Wardman M, Chintakayala PK, de Jong G. Values of travel time in Europe: review and meta-analysis. Transp Res Part A Policy Pract. 2016 Dec;94:93-111. doi: 10.1016/j.tra.2016.08.019