She, Dongli Li, et al. “Temporal Changes of an Alfalfa Succession and Related Soil Physical Properties on the Loess Plateau, China”. Pesquisa Agropecuaria Brasileira, vol. 44, no. 2, Nov. 2010, pp. 189-96, doi:10.1590/S1678-3921.pab2009.v44.799.