Dmitrienko VT, Zvyagin VG. Index of solution set for perturbed Fredholm equations and existence of periodic solutions for delay differential equations. TMNA [Internet]. 2003 Mar. 1 [cited 2024 Jul. 22];21(1):53-80. Available from: https://apcz.umk.pl/TMNA/article/view/TMNA.2003.004