Wittaya Piya-Arayanan และ Sunti Tirapat. (2007) Credit rating change and change in firm’s probabilities of default. Chulalongkorn University:ม.ป.ท.Wittaya Piya-Arayanan และ Sunti Tirapat. 2007. Credit rating change and change in firm’s probabilities of default. ม.ป.ท.:Chulalongkorn University;Wittaya Piya-Arayanan และ Sunti Tirapat. Credit rating change and change in firm’s probabilities of default. ม.ป.ท.:Chulalongkorn University, 2007. Print.