M. S. Rahman, M. A. Rahman, A. K. Mondal, M. Rani, M. A. K. Azad, and M. Asadullah, “A Comparative Study of the Transient Response Characteristics of Laboratory-Scale Spray Columns and Packed Columns”, Pakistan Journal of Scientific & Industrial Research, vol. 49, no. 1, pp. 19–22, Feb. 2006.