@article{DAN_1989_306_3_a9,
     author = {S. V. Emel'yanov and S. K. Korovin and S. V. Nikitin and M. G. Nikitina},
     title = {Observers and differentiators of the output of nonlinear systems},
     journal = {Doklady Akademii Nauk},
     pages = {556--560},
     publisher = {mathdoc},
     volume = {306},
     number = {3},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1989_306_3_a9/}
}