Christensen T, Riis AH, Hatch EE, Wise LA, Nielsen MG, Rothman KJ, Toft Sorensen H, Mikkelsen EM. Costs and efficiency of online and offline recruitment methods: a web-based cohort study. J Med Internet Res. 2017 Mar 1;19(3):e58. doi: 10.2196/jmir.6716
Arana A, Cuchi T, Arellano F. Strengthening EU pharmacovigilance. European pharmaceutical contractor. European pharmaceutical contracto: EPC. 2009;44-5.