Volume 21.2, Issue 42, May 1989, Pages 101-108
Y. HEFNAWY; R.S. REFAI; SABAH MOUSTAFA
Volume 21.1, Issue 41, January 1989, Pages 134-139
Y. HEFNAWY; SABAH MOUSTAFA; R.S. REFAI
Volume 19.2, Issue 38, January 1988, Pages 90-97
H. ABDEL-RAHMAN; T. EL-KHATEIB; R.S. REFAI