Joezy-ShekalgorabiS., ShadparvarA. A., De VriesA., and GayK. D. “The Extent of Increase in First Calving Age As a Result of Implementing Various Sexed Semen Breeding Strategies”. Spanish Journal of Agricultural Research, Vol. 12, no. 1, Jan. 2014, pp. 106-1, doi:10.5424/sjar/2014121-4516.