Calamari, C. V., Ferrari, S., Leinz, F. F., Rodrigues, C. F. de C., Bianchini, D., Ferreira, F., & Dias, R. A. (2003). Evaluation of two methods for early pregnancy diagnosis in ewes: transrectal ultrasonography and pregnancy detector for small ruminant (DPPR-80®). Brazilian Journal of Veterinary Research and Animal Science, 40(4), 261-266. https://doi.org/10.1590/S1413-95962003000400004