1. Ash, R. W.: A large-diameter rumen cannula for sheep. J. Physiol. (Lond.) 139, 6 P (1957).
2. -- The flow of food material from the omasum of sheep. J. Physiol. (Lond.) 164, 25 P (1962).
3. Ash, R. W., and R. N. B. Kay: Digestive secretions and the flow of food material in the sheep. In: Progress in nutrition and allied sciences, p. 127. Ed. by D. P. Cuthbertson. Edinburgh, London: Oliver and Boyd 1963.
4. Boyne, A. W., R. M. Campbell, J. Davidson and D. P. Cuthbertson: Changes in composition of the digesta along the elimentary tract of sheep. Brit. J. Nutr. 10, 325 (1956).
5. Butler, F. E.: Determination of tritium in water and urine. Analyt. Chem. 33, 409 (1961).