Franklin JM, Dejene S, Huybrechts KF, Wang SV, Kulldorff M, Rothman KJ. A bias in the evaluation of bias comparing randomized trials with nonexperimental studies. Epidemiol Methods. 2017 Apr;6(1):20160018.. doi: 10.1515/em-2016-0018.
Webster AJ, Saville C, Church BM, Gnanasakthy A, Moss R. Some effects of different rearing systems on health, cleanliness and injury in calves. Vet J. 1985 Sep;141(5):472-83.
Webster AJ, Saville C, Church BM, Gnanasakthy A, Moss R. The effect of different rearing systems on the development of calf behaviour. Vet J. 1985 May;141(3):249-64.