Sopapan Ngerncham และ Sungkom Jongpiputvanich. (2009) Rate of breastfeeding for 4 months and promoting factors : a cohort study of mothers of preterm infants at Siriraj Hospital. Chulalongkorn University:ม.ป.ท.Sopapan Ngerncham และ Sungkom Jongpiputvanich. 2009. Rate of breastfeeding for 4 months and promoting factors : a cohort study of mothers of preterm infants at Siriraj Hospital. ม.ป.ท.:Chulalongkorn University;Sopapan Ngerncham และ Sungkom Jongpiputvanich. Rate of breastfeeding for 4 months and promoting factors : a cohort study of mothers of preterm infants at Siriraj Hospital. ม.ป.ท.:Chulalongkorn University, 2009. Print.