@article{RM_2013_68_5_a1,
     author = {P. G. Grinevich and S. P. Novikov},
     title = {Discrete $SL_n$-connections and self-adjoint difference operators on two-dimensional manifolds},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {861--887},
     publisher = {mathdoc},
     volume = {68},
     number = {5},
     year = {2013},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_2013_68_5_a1/}
}