Lavan Southisan. (1998) Regional differentials of birth spacing practice in Lao People's Democratic Republic. Mahidol University,:ม.ป.ท.Lavan Southisan. 1998. Regional differentials of birth spacing practice in Lao People's Democratic Republic. ม.ป.ท.:Mahidol University,;Lavan Southisan. Regional differentials of birth spacing practice in Lao People's Democratic Republic. ม.ป.ท.:Mahidol University, 1998. Print.