Ketkeo Boupha. (1999) Smoking prevalence and its correlates on smoking behavior among male secondary school children in Viantaine Municipality, Lao PDR. Mahidol University,:ม.ป.ท.Ketkeo Boupha. 1999. Smoking prevalence and its correlates on smoking behavior among male secondary school children in Viantaine Municipality, Lao PDR. ม.ป.ท.:Mahidol University,;Ketkeo Boupha. Smoking prevalence and its correlates on smoking behavior among male secondary school children in Viantaine Municipality, Lao PDR. ม.ป.ท.:Mahidol University, 1999. Print.