Galvez, M.C.D., Vallar, E.A. and Alarcon, M.C. 1994. Differential absorption lidar for measurement of SO2 in the atmosphere. Proceedings of the Samahang Pisika ng Pilipinas, 12(1), SPP-1994-IP-08. URL: https://proceedings.spp-online.org/article/view/SPP-1994-IP-08.