@article{DAN_1974_217_1_a3,
     author = {E. I. Zverovich and L. I. Pomerantseva},
     title = {The {Riemann} problem for n pairs of functions with matrices of permutation type},
     journal = {Doklady Akademii Nauk},
     pages = {20--23},
     publisher = {mathdoc},
     volume = {217},
     number = {1},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1974_217_1_a3/}
}