1. Fradkov A.L.: Speed-gradient scheme and its application in adaptive control problems. Autom. Remote Control 40(9), 1333–1342 (1980) (Translated from Avtomat. i Telemekh., 1979, issue 9, 90–101)
2. Fomin, V.N., Fradkov, A.L., Yakubovich, V.A.: Adaptive control of dynamical plants, Nauka, M. (1981), (in Russian)
3. Fradkov, A.L., Stotsky A.: Speed gradient adaptive control algorithms for mechanical systems. Int. J. Adapt. Control Signal Process. 6(3), 211–220 (1992). http://dx.doi.org/10.1002/acs.4480060309
4. Andrievskij, B., Guzenko, P., Fradkov, A.L.: Control of nonlinear oscillations in mechanical systems by the steepest gradient method. Autom. Remote Control 57(4), 456–467 (1996)
5. Andrievsky, B., Konoplev, V., Koniukhov, A., Fradkov, A.L.: Control, state estimation and laboratory experiments with oscillatory mechanical system. IFAC Proc. Vol. 31(17), 735–738 (1998). https://www.sciencedirect.com/science/article/pii/S1474667017404265