“…The problem of feedback stabilization of some classes of linear and nonlinear systems has been investigated in case of bounded and unbounded control operators in [2,3,4,5,6,7,8,9]. Feedback stabilization of the bilinear system (3) has been investigated in the case of a bounded control operator by numerous authors using various control approaches, such as quadratic control laws, sliding mode control, piecewise constant feedback and optimal control laws (see [10,31] and the references therein). Recently, the question of stabilization of bilinear systems with unbounded control operator has been treated in [12,18,19,30].…”