1. Ahmad, I.A., Lin, P.E.: Nonparametric sequential estimation of a multiple regression function. Bull. Math. Statist. 17, 63?75 (1976)
2. Barlow, Bartholomew, Bremner, Brunk: Statistical Inference under Order Restrictions. New York: John Wiley 1972
3. Benedetti, J.: On the nonparametric estimation of regression function. J. Roy. Statist. Soc. B39, 248?253 (1977)
4. Cheng, K.F.: Strong convergence in nonparametric estimation of regression functions. Florida State University Statistics Report M510 (ONR Technical Report No. 143) (1979)
5. Clark, R.M.: Nonparametric estimation of a smooth regression function. J. Roy. Statist. Soc. B39, 107?113 (1977)