Hai, N.D., Nghia, N.X., Dang, N.X., Phuong, D.H. and Toan, N.M. 2016. The status of indochinese grey langur Trachypithcus crepusculus at Xuan Lien nature reserve, Thanh Hoa province. Academia Journal of Biology. 38, 2 (Apr. 2016), 162–170. DOI:https://doi.org/10.15625/0866-7160/v38n2.7890.