Lyapunov exponents from observed time series
Paul Bryant, Reggie Brown, and Henry D. I. Abarbanel
Phys. Rev. Lett. 65, 1523 (1990) - Published 24 September, 1990
Shadowing of physical trajectories in chaotic dynamics: Containment and refinement
Celso Grebogi, Stephen M. Hammel, James A. Yorke, and Tim Sauer
Phys. Rev. Lett. 65, 1527 (1990) - Published 24 September, 1990