Oscillation criteria for retarded differential equations with a nonlinear damping term. S.R. Grace — 1996 Aequationes mathematicae
Oscillation theorems for second order nonlinear differential equations with deviating arguments. Grace, S.R.; Lalli, B.S. — 1987 International Journal of Mathematics and Mathematical Sciences
On the oscillation of certain second-order differential equations. Agarwal, Ravi P.; Grace, S.R. — 2000 Georgian Mathematical Journal