@article{RM_1984_39_2_a1,
     author = {A. K. Zvonkin and M. A. Shubin},
     title = {Non-standard analysis and singular perturbations of~ordinary differential equations},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {69--131},
     publisher = {mathdoc},
     volume = {39},
     number = {2},
     year = {1984},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1984_39_2_a1/}
}