Doumer, M. E., Giacomini, S. J., Silveira, C. A. P., Weiler, D. A., Bastos, L. M., & de Freitas, L. L. (2012). Microbial and enzymatic activities in the soil after application of retorted oil shale. Pesquisa Agropecuaria Brasileira, 46(11), 1538–1546. https://doi.org/10.1590/S1678-3921.pab2011.v46.10220