Thu, Do Van, Doan Viet Binh, Tran Xuan Khoi, and Le Thi Hue. 2017. “Research Bac Ha Dog Semen Frozen in Liquid Nitrogen -196oC”. Academia Journal of Biology 39 (2):236-44. https://doi.org/10.15625/0866-7160/v39n2.8867.