Viana CHC, Arruda RP de, Moretti AS, Visintin JA. Ovarian cysts, rectal palpation and ultra-rectal ultra- sonography diagnosis in sows: literature review and two clinical report studies. Braz. J. Vet. Res. Anim. Sci. 1998;35(2):64-68. doi:10.1590/S1413-95961998000200003