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
Clarkson TB, Anthony MS, Klein KP. Effects of estrogen treatment on arterial wall structure and function. Drugs. 1984;47(Suppl 2):42-51.