Yongdong Zhao and Suhada Jayasuriya, "A frequency domain criterion for robustly stabilizing a family of interval plants", Transactions of the ASME, 1995, Vol. 117, pp. 98-104.

Yongdong Zhao and Suhada Jayasuriya, "Frequency domain criteria for synthesizing robustly stabilizing compensators for a class of interval plants", Journal of Dynamical Systems, Measurement, and Control, 1995, Vol. 117, pp. 241-247.

New control methods are proposed for stabilizing a system $${d^nx\over dt^n}+b_{n-1}{d^{n-1}x\over dt^{n-1}}+...+b_0= {d^mu\over dt^m}+a_{m-1}{d^{m-1}u\over dt^{m-1}}+...+a_0$$ ($x$ - state, $u$ - control), in which the values $b_i$ that describe the dependency on the control are known precisely, while for the values $a_i$ that describe the "inertia" of the system (i.e., its dependence on the past states) we only know {\it intervals} of possible values.