[1] M. Švec:
Behavior of nonoscillatory solutions of some nonlinear differential equations. Acta Mathematica U. C. XXXIX (1980), 115–130.
MR 0619268
[3] V. Šeda:
Nonoscillatory solutions of differential equations with deviating argument. Czech. Math. J. 36(111) (1986), .
MR 0822871