Optimal control for n × n hyperbolic systems involving operators of infinite order Hussain A. El-Saify; G. M. Bahaa — 2002 Mathematica Slovaca
Optimal control for n × n coupled systems governed by Petrowsky type equations with control-constrained and infinite number of variables Hussain A. El-Saify; G. M. Bahaa — 2003 Mathematica Slovaca
Boundary control problem with an infinite number of variables. El-Saify, Hussain A. — 2001 International Journal of Mathematics and Mathematical Sciences