On the existence of nonoscillatory solutions tending to zero at ? for differential equations with positive delays

T. Kusano andH. Onose, Asymptotic behavior of nonoscillatory solutions of functional differential equations of arbitrary order. J. London Math. Soc.14, 106?112 (1976).

T. Kusano andH. Onose, Nonoscillation theorems for differential equations with deviating argument. Pacific J. Math.63, 185?192 (1976).

G. Ladas. Sharp conditions for oscillations caused by delays. Applicable Anal.9, 93?98 (1979).

G.Ladas, V.Akshmikantham and J. S.Papadakis, Oscillations of higher-order retarded differential equations generated by the retarded argument. Symposium on delay and functional differential equations, University of Utah, March 7?11, 1972.

D. L. Lovelady, Positive bounded solutions for a class of linear delay differential equations. Hiroshima Math. J.6, 451?456 (1976).

Ch. G. Philos, Oscillatory and asymptotic behavior of all solutions of differential equations with deviating arguments. Proc. Roy. Soc. Edinburgh Sect. A,81, 195?210 (1978).

Ch. G. Philos andV. A. Staikos, Asymptotic properties of nonoscillatory solutions of differential equations with deviating argument. Pacific J. Math.70, 221?242 (1977).

Y. G. Sficas, Strongly monotone solutions of retarded differential equations. Canad. Math. Bull.22, 403?412 (1979).

Y. G. Sficas, On the behavior of nonoscillatory solutions of differential equations with deviating argument. J. Nonlinear Anal.3, 379?394 (1979).