1. Strategic sensors and spy sensors;L. Afifi;International Journal of Applied Mathematics and Computer Science,1994
2. Spy sensors and detection;L. Afifi;International Journal of Systems Science,1995
3. Enlarged exact compensation in distributed systems;L. Afifi;International Journal of Applied Mathematics and Computer Science,2002a
4. Regionally efficient and strategic actuators;L. Afifi;International Journal of Systems Science,2002b