@article{DE_1997_33_10_a8,
     author = {Yu. V. Pokorny and R. Mustafokulov},
     title = {On the positive invertibility of some boundary value problems for a fourth-order equation},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1358--1365},
     publisher = {mathdoc},
     volume = {33},
     number = {10},
     year = {1997},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1997_33_10_a8/}
}