Knapp AK, Hoover DL, Blair JM, et al. A test of two mechanisms proposed to optimize grassland aboveground primary productivity in response to grazing. Journal of Plant Ecology. 2012;5:357 -365. doi:10.1093/jpe/rts020.

Buis G. Controls of aboveground net primary production in mesic savanna grasslands: An inter-hemispheric comparison.  2009;MS Thesis:1 -50. doi:10.1007/s10021-009-9273-1.