1. 1. M. Numan, E. Knobil, and J. D. Neill, 1994 . InThe Physiology of Reproduction . Vol. 2, 221 -302 . Raven Press. New York, NY.
2. 2. A. Fleming, G. Orpen, A. Fogel, and G. F. Melson, 1986 . InOrigins of Nurturance . : 141 -207 . Lawrence Erlbaum Associates. Hillside, NJ.
3. A comparative systems model of the regulation of maternal motivation in mammals
4. 4. J. S. Rosenblatt, A. D. Mayer, K. E. Hood, G. Greenberg, and E. Tobach, 1995 . InBehavioral Development . : 177 -230 . Garland Press, NY.
5. Timidity prevents the virgin female rat from being a good mother: Emotionality differences between nulliparous and parturient females