@article{SM_1980_36_1_a1,
     author = {N. E. Tovmasyan},
     title = {On~removable singular points of elliptic systems of second order differential equations in the plane},
     journal = {Sbornik. Mathematics},
     pages = {21--29},
     year = {1980},
     volume = {36},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1980_36_1_a1/}
}