Benjamat Hantanong. (2007) Incidence and risk factors of preterm delivery at Ramathibodi hospital : 2005-2006. Mahidol University,:ม.ป.ท.Benjamat Hantanong. 2007. Incidence and risk factors of preterm delivery at Ramathibodi hospital : 2005-2006. ม.ป.ท.:Mahidol University,;Benjamat Hantanong. Incidence and risk factors of preterm delivery at Ramathibodi hospital : 2005-2006. ม.ป.ท.:Mahidol University, 2007. Print.