Hatvani, L.: Asymptotic stability conditions for a linear nonautonomous delay differential equation., (Martelli, Mario (ed.) et al., Differential equations and applications to biology and to industry. Proceedings of the Claremont international conference dedicated to the memory of Stavros Busenberg (1941--1993), Claremont, CA, USA, June 1--4, 1994. Singapore: World Scientific. 181-190 (1996). [ISBN 981-02-2233-5/hbk])
Hatvani, L.: Periodic solutions of nonlinear functional differential equations., (Yoshizawa, T. (ed.) et al., Proceedings of the international symposium on functional differential equations, Kyoto, Japan, 30 August - 2 September 1990. Singapore: World Scientific. 120-126 (1991). [ISBN 981-02-0457-4])
Hatvani, L.: On the asymptotic stability of the equilibrium of the damped oscillator., (Wiener, Joseph (ed.) et al., Ordinary and delay differential equations 1. Proceedings of the international conference on theory and applications of differential equations, held at the University of Texas-Pan American, Edinburg, TX, USA, on May 15-18, 1991. Harlow, Essex: Longman Scientific \& Technical. Pitman Res. Notes Math. Ser. 272, 68-72 (1993). [ISBN 0-582-09113-6])
Hatvani, L\'aszl\'o: On the asymptotic stability in differential systems by Lyapunov direct method., (Lakshmikantham, V. (ed.), World congress of nonlinear analysts '92. Proceedings of the first world congress, Tampa, FL, USA, August 19-26, 1992. 4 volumes. Berlin: de Gruyter. 1341-1348 (1996). [ISBN 3-11-013215-X/hbk])
Hatvani, L\'aszl\'o: On Lyapunov's direct method for nonautonomous functional differential equations., (Ladde, G. S. (ed.) et al., Dynamic systems and applications. Volume 3. Proceedings of the 3rd international conference, Morehouse College, Atlanta, GA, USA, May 26-29, 1999. Atlanta, GA: Dynamic Publishers. 297-304 (2001). [ISBN 0-96-403983-4/hbk])