Puttipong Khawnual และผู้แต่งคนอื่นๆ. (2006) Relationship between Serum Progesterone and faecal progestins in the pregnant and non-pregnant Asian elephant (Elephas maximus). Chulalongkorn University:ม.ป.ท.Puttipong Khawnual และผู้แต่งคนอื่นๆ. 2006. Relationship between Serum Progesterone and faecal progestins in the pregnant and non-pregnant Asian elephant (Elephas maximus). ม.ป.ท.:Chulalongkorn University;Puttipong Khawnual และผู้แต่งคนอื่นๆ. Relationship between Serum Progesterone and faecal progestins in the pregnant and non-pregnant Asian elephant (Elephas maximus). ม.ป.ท.:Chulalongkorn University, 2006. Print.