1. New methods for non-linear filtering;Bucy;Rev. Fr. Autom. Inf. Rech. Oper,1973
2. Non-linear bayesian estimation using gaussian sum approximations;Alspach;IEEE Trans. Autom. Control,1972
3. Spline filters;Figueiredo,1971
4. Non-linear filter representation via spline functions;Bucy,1974
5. The Theory of Splines and Their Applications;Ahlberg,1967