Existence theorems for nonlinear functional differential equations of neutral type. Kitamura, Yuichi; Kusano, Takaši; Lalli, B.S. — 1995 Georgian Mathematical Journal
Vanishing Oscillations of Solutions of a Class of Differential Systems with Retarded Argument Yuichi Kitamura; Takaŝi Kusano — 1977 Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Si dànno condizioni sufficienti perché tutte le traiettorie oscillatorie del sistema differenziale x ′ ( t ) = p ( t ) y ( t ) , y ′ ( t ) = f ( t , x ( g ( t ) ) ) tendano a zero quando t → ∞ .
Nonoscillation theorems for functional differential equations of arbitrary order. Graef, John R.; Grammatikopoulos, Myron K.; Kitamura, Yuichi; Kusano, Takaŝi; Onose, Hiroshi; Spikes, Paul W. — 1984 International Journal of Mathematics and Mathematical Sciences