CONTRERAS, P. A., F. WITTWER, V. RUIZ, A. ROBLES, and H. BRÖHMWALD. 1999. “Blood Values of Thyroxine and Triiodothyronine in Grazing Friesian Cows”. Archivos De Medicina Veterinaria 31 (2):205-10. https://doi.org/10.4067/S0301-732X1999000200007.