@article{VMJ_2017_19_4_a3,
     author = {S. I. Mitrokhin},
     title = {A periodic boundary value problem for a fourth order differential operator with a summable potential},
     journal = {Vladikavkazskij matemati\v{c}eskij \v{z}urnal},
     pages = {35--49},
     publisher = {mathdoc},
     volume = {19},
     number = {4},
     year = {2017},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMJ_2017_19_4_a3/}
}