Miyazawa, Mário, et al. “Cobalt Determination in Bovine Faeces by Extraction With 1M HCL”. Pesquisa Agropecuaria Brasileira, vol. 27, no. 10, Oct. 1992, pp. 1415-9, doi:10.1590/S1678-3921.pab1992.v27.3786.