1. Cognie Y, Mauleon P: Control of Reproduction in the Ewe, In: Sheep Production (Nottingham Easter School proceedings) 35 Butterworths, London, 1983, 381–392.
2. Durotoye LA, Rajkumar R, Argo CM, Nowak R, Webley GE, McNeil ME, Graham NB, Rodway RG: Effect of constant-release melatonin implants on the onset of oestrus activity and on reproductive performance in the ewe. Anim. Prod. 1991, 52, 489–497.
3. English J, Poulton AL, Arendt J, Symons AMA: A comparison of the efficiency of treatments in advancing oestrus in ewes. J. Reprod. Fert. 1986, 77, 321–327.
4. Fogarty NM, Dickerson GE, Young LD: Lamb production and its components in pure breeds and composite lines. I. Seasonal and other environmental effects. J. Anim. Sci. 1984, 58, 285–300.
5. Freeman DH: Applied Categorical Data Analysis. Marcel Dekker, Inc., New York and Basel, 1987, 81–94.