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
Graham JE, Rouse M, Twiss J, McKenna SP, Vidalis AA. Greek adaptation and validation of the Ankylosing Spondylitis Quality of Life (ASQoL) measure. Hippokratia. 2015;19(2):119-24.