@article{iiasa4689,
          volume = {6},
          number = {3},
           title = {Ellipsoidal calculus, singular perturbations and the state estimation problems for uncertain systems},
       publisher = {Birkhauser Verlag},
            year = {1996},
           pages = {323--338},
         journal = {Journal of Mathematical Systems, Estimation, and Control},
             url = {https://pure.iiasa.ac.at/id/eprint/4689/},
            issn = {1052-0600},
          author = {Filippova, T. F. and Kurzhanski, A. B. and Sugimoto, K. and Valyi, I.}
}