Volume 9, Issue 17.18, January 1982, Pages 109-113
H. YOUSSEF; A.A.M. EL-TIMAWY
Volume 8, Issue 15.16, January 1981, Pages 115-119
H. YOUSSEF
Volume 8, Issue 15.16, January 1981, Pages 121-125
H. YOUSSEF
Volume 7.1, Issue 13.14, January 1980, Pages 139-147
M.A.M. FAHMY; R. KHALIFA; H. YOUSSEF