@article{SM_1975_25_4_a4,
     author = {A. M. Il'in and E. F. Lelikova},
     title = {A~method of joining asymptotic expansions for the equation $\varepsilon\Delta u-a(x,y)u_y=f(x,y)$ in a~rectangle},
     journal = {Sbornik. Mathematics},
     pages = {533--548},
     publisher = {mathdoc},
     volume = {25},
     number = {4},
     year = {1975},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1975_25_4_a4/}
}