Посилання:Periodic boundary-value problem for third-order linear functional differential equations / R. Hakl // Український математичний журнал. — 2008. — Т. 60, № 3. — С. 413–425. — Бібліогр.: 20 назв. — англ.
Підтримка:The research was supported by the Academy of Sciences of the Czech Republic, Institutional Research
Plan No. AV0Z10190503 and the Grant No. 201/06/0254 of the Grant Agency of the Czech Republic.