Ríos-Utrera, Ángel, R. C. Calderón-Robles, J. V. Rosete-Fernández, and J. Lagunes-Lagunes. “Genetic and Phenotypic Correlations Among Reproductive Traits of Dairy Cows”. Agronomía Mesoamericana, vol. 21, no. 2, Dec. 2010, pp. 235-44, doi:10.15517/am.v21i2.11835.