1. Commutativity of time-varying systems
2. Comments on ‘ Commutativity of second-order time-varying systems ’
3. M. E. Koksal, General Commutativity Conditions for Time-Varying Systems (2nd National Congress of Electrical Engineers. Ankara, Turkey, 1987), pp 566–569.
4. M. E. Koksal, “Commutativity of 4th order systems and euler systems,” in Symposium of Yildiz Technical University on the Role of Engineering on the Development of our Country (lstanbul, 1988), pp 398–408
5. Commutativity of Linear Time-Varying Differential Systems with Nonzero Initial Conditions: A Review and Some New Extensions