1992
- ▪R. Schwarzschild, E.D. Sontag, M.L.J. Hautus, "Output-Saturated Systems", In Proc.\ Amer.\ Automatic Control Conf.\ \/, Chicago, June 1992, pp. 2504–2509, 1992.
1991
- ▪R. Schwarzschild, E.D. Sontag, "Quantized systems, saturated measurements, and sign-linear systems", In Proc.\ Conf.\ Inform.\ Sci.\ and Systems, John Hopkins University, March 1991, pp. 134–139, 1991.
- ▪R. Schwarzschild, E.D. Sontag, "Algebraic theory of sign-linear systems", In Proc.\ Amer.\ Automatic Control Conf.\/, Boston, June 1991, pp. 799–804, 1991.