Allaye-Chan, A. C., White, R. G., Holleman, D. F. and Russell, D. E. (1990) “Seasonal concentrations of cesium-137 in rumen content, skeletal muscles and feces of caribou from the Porcupine herd: lichen ingestion rates and implications for human consumption”, Rangifer, 10(3), pp. 17–24. doi: 10.7557/2.10.3.816.