de Carvalho, J.R.P. and Mead, R. 1992. Estimation of the population covariance coefficient for split-plot experiments. Pesquisa Agropecuaria Brasileira. 27, 6 (Jun. 1992), 805–815. DOI:https://doi.org/10.1590/S1678-3921.pab1992.v27.3714.