Foz Filho, R.P. de P., Fernandes Filho, A. and Borelli, V. (1999) “Morphological aspects of the spermatic cord in mules (Equus asinus x Equus caballus)”, Brazilian Journal of Veterinary Research and Animal Science, 36(4), pp. 183–187. doi:10.1590/S1413-95961999000400003.