Hindson J C
Vet Rec. 1978 Apr 15;102(15):327-32. doi: 10.1136/vr.102.15.327.
Measurements of factors involved in the degree of traction exerted during obstetric cases were carried out. Bovine material force was approximately 150 lbs. Maximum manual effort would be approximately four times this and mechanical traction would be at least 50 per cent higher again. A workable maternal fetal ratio was established for use in cases of fetal oversize. Possible quantification of other factors is also discussed.
对产科病例中所施加牵引力程度相关因素进行了测量。牛的物力约为150磅。最大人力约为此的四倍，而机械牵引至少还要再高50%。建立了一个可行的母胎比例，用于胎儿过大的病例。还讨论了其他因素进行量化的可能性。
