@article{DE_1989_25_11_a16,
     author = {P. Burgmeier},
     title = {Controllability of systems with distributed parameters that can be described by $m$th-order {Goursat--Darboux} systems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1947--1956},
     publisher = {mathdoc},
     volume = {25},
     number = {11},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1989_25_11_a16/}
}