ThanhN. V., HangP. T., GioiP. V., ToanN. C., and LongS. T. “The Relationship Between Plasma Progesterone Concentration on Day 6 After Artificial Insemination and Pregnancy Rate of Dairy Cows in Vietnam”. Tropical Animal Science Journal, Vol. 46, no. 2, May 2023, pp. 146-50, doi:10.5398/tasj.2023.46.2.146.