R. F. Miller, Haferkamp, M. Roy, and Angell, R. F.,
“Clipping Date Effects on Soil Water and Regrowth in Crested Wheatgrass”,
Journal of Range Management, vol. 43, no. 3, p. 253, 1990.
T. Svejcar, Angell, R. F., Bradford, J. A., Dugas, W., Emmerich, W., Frank, A. B., Gilmanov, T. G., Haferkamp, M. Roy, Johnson, D. A., Mayeux, H., and , “Carbon fluxes on North American rangelands”,
Rangeland Ecology & Management, vol. 61, pp. 465–474, 2008.