1. R. Bachmann, L. Brull, Th. Mrzigold, and U. Pallaske. On methods for reducing the index of differential algebraic equations. Comput. chem. Engng., 14:1271–1273, 1990.
2. V. B. Bajic. Lyapunov’s Direct Method in The Analysis of Singular Systems and Networks. Shades Technical Publications, Hillcrest, Natal, 1992.
3. K. E. Brenan, S. L. Campbell, and L. R. Petzold. Numerical Solution of Initial-Value Problems in Differential-Algebraic Equations. Classics in Applied Mathematics. Society for Industrial and Applied Mathematics, Philadelphia, 1996.
4. Research Notes in Mathematics;SL Campbell,1982
5. S. L. Campbell. Consistent initial conditions for singular and nonlinear systems. Circ. Sys. Signal Proc, 2:45–55, 1983.