YASMEEN, G., HAFEEZ, S., IKRAM, N., ANSARI, T.M., KHATTAK, A. K., AND AFZAL, M.. "Characterization of Metal Exchanged Zeolite-A using Quantasorb and Mercury Porosimeter" Pakistan Journal of Analytical & Environmental Chemistry [Online], Volume 5 Number 1 (1 June 2004)