Preston T R 1971 Quantitative aspects of animal protein production from NPN in ruminants Source:FAO/IAEA. Tracer studies on non-protein nitrogen for ruminants. http://www.utafoundation.org/preston.papers/Preston1971(IAEA).pdf
Preston T R and Leng R A 1987: Matching ruminant production systems with available resources in the tropics and sub-tropics (2009 New online edition). Penambul Books Armidale http://www.utafoundation.org/P&L/preston&leng.pdf
Leng R A and Preston T R 2010: Further considerations of the potential of nitrate as a high affinity electron acceptor to lower enteric methane production in ruminants. Livestock Research for Rural Development. Volume 22, Article #221. http://www.lrrd.org/lrrd22/12/leng22221.htm
Preston T R 2010 Production of food, feed and energy in a carbon-negative farming system. http://www.mekarn.org/workshops/pakse/html/preston.htm
Whitelaw F G, Preston T R and Dawson G S 1962 The nutrition of the early-weaned calf a comparison of commercial groundnut meal, heat-treated groundnut meal and fish meal as the major protein source in the diet. Animal Production Volume 4. http://www.utafoundation.org/publications/whitelaw&preston 1962.pdf