Volume 20.2, Issue 40, September 1988, Pages 20-23
S.M. EL-MAGAWRY; LA. IBRAHIM; M.F. DOWIDAR; M.A. YOUSIF
Volume 17.1, Issue 33, May 1986, Pages 86-95
M.A. YOUSIF; H.M. EL-ATTAR; ABDEL-RAOUF M. MAHMOUD; S. EL-MAGAWRY