Ngarmcherd Danpattanamongkon และ Yupaporn Kemprasit. (2011) BQ-elements of some semigroups. Chulalongkorn University:ม.ป.ท.Ngarmcherd Danpattanamongkon และ Yupaporn Kemprasit. 2011. BQ-elements of some semigroups. ม.ป.ท.:Chulalongkorn University;Ngarmcherd Danpattanamongkon และ Yupaporn Kemprasit. BQ-elements of some semigroups. ม.ป.ท.:Chulalongkorn University, 2011. Print.