%0 Journal Article %A Ya. M. Dymarskii %A A. A. Bondar' %T An eigenfunction manifold generated by a family of periodic boundary value problems %J Sbornik. Mathematics %D 2021 %P 1208-1227 %V 212 %N 9 %U http://geodesic.mathdoc.fr/item/SM_2021_212_9_a1/ %G en %F SM_2021_212_9_a1