Selected papers relating to Kalman-Yakubovich-Popov Lemma
S.V.Gusev (2006) "Fenchel Duality, S-procedure and Yakubovich-Kalman Lemma," Automation and Remote Control, No.2, pp. 135--153.

S.V.Gusev (2005) "Extended Kalman-Yakubovich-Popov Lemma in a Hilbert Space and Fenchel Duality," Proc. of the 44th CDC and ECC'05, Seville, pp. 1565--1570.

S.V.Gusev (2005) "The Structure of Semi-definite Solutions of Homogeneous Generalized Lyapunov Equation and Frequency Domain Theorem in a Hilbert Space," Vestnic St.Petersburg University: Mathematics, No. 3, pp. 16--23.