Geuijen P, de Rond M, Kuppens J, Atsma F, Schene A, de Haan H, et al. Physicians' norms and attitudes towards substance use in colleague physicians: A cross-sectional survey in the Netherlands. PLOS ONE. 2020 Apr 3;15(4):e0231084. doi: 10.1371/journal.pone.0231084.