Hayes AF, Rockwood NJ. Regression-based statistical mediation and moderation analysis in clinical research: observations, recommendations, and implementation. Behav Res Ther. 2017 Nov;98:39-57. doi: 10.1016/j.brat.2016.11.001
Lawson DH, Jick H, Rothman KJ. Coffee and tea consumption and breast disease. Surgery. 1981 Jan 1;90(5):801-3.