1. Altman, P. L., Dittmer, D. S. (eds.): Respiration and Circulation. Fed. Am. Soc. Exp. Biol., Bethesda, Md., pp. 509?511, 1971
2. Bailey, D. J.: Counter-current flow of maternal and foetal blood streams in guinea-pig placenta. J. Physiol. (Lond.)242, 104P-105P (1974)
3. Bjellin, L., Sj�quist, P.-O. B., Carter, A. M.: Uterine, maternal placental and ovarian blood flow throughout pregnancy in the guinea-pig. Z. Geburtsh. Perinat.179, 179?187 (1975)
4. Blechner, J. N., Meschia, G., Barron, D. H.: A study of the acid-base balance of fetal sheep and goats. Q. J. Exp. Physiol.45, 60?71 (1960)
5. Daniel, S., Karlis, S., Stanley, D.: Lactase and pyruvate as an index of prenatal oxygen deprivation. Pediatrics37, 942?953 (1966)