1. Linear filtering of singularly perturbed systems;Haddad;IEEE Trans. Aut. Control,1976
2. Boundary layer method for optimal control of singularly perturbed systems;Wilde,1972
3. Singular perturbations and order reduction in control theory an overview;Kokotović;Automatica,1976
4. On a singular perturbation problem in linear filtering theory;Haddad,1971
5. On singular perturbation in linear filtering and smoothing;Haddad,1974