1. A note on asymptotic behavior of differential equations;Bellman;Boll. Un. Mat. Ital.,1963
2. Note on Riccati equation;Calogero;J. Math. Phys.,1963
3. Quasilinearization and Nonlinear Boundary-Value Problems;Bellman,1965
4. On nonlinear differential equations, the maximum operation, and monotone convergence;Kalaba;J. Math. Mech.,1959
5. Stability of circuits with randomly time-varying parameters;Bertram;IRE Trans. Circuit Theory,1959