Volume 21.2, Issue 42, May 1989, Pages 44-47
M.K. IBRAHIM; MAHMOUD A.Z.
Volume 21.1, Issue 41, January 1989, Pages 93-96
M.K. IBRAHIM; MAHMOUD A.Z.; R. KHALIFA
Volume 21.1, Issue 41, January 1989, Pages 97-101
MAHMOUD A.Z.; M.K. IBRAHIM