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
Vekeman F, Gauthier-Loiselle M, Faust E, Lefebvre P, Lahoz R, Duh MS, Sacco P. Patient and caregiver burden associated with fragile x syndrome in the United States. Am J Intellect Dev Disabil. 2015 Sep;120(5):444-59. doi: 10.1352/1944-7558-120.5.444