Oscillation criteria for second-order nonlinear differential equations with integrable coefficient

In this paper, we consider the second-order nonlinear differential equation [a(t)\y'(t)\(sigma -1)y'(t)]'+q(t)f(y(t))=r(t), where sigma > 0 is a constant, a is an element of C(R, (0, infinity)), q is an element of C(R, R), f is an element of C(R, R), xf(x) > 0, f'(x) greate r than or equal to 0 for x not equal 0. Some new sufficient conditions for the oscillation of all solutions of (*) are obtained. Several examples whic h dwell upon the importance of our results are also included. (C) 2000 Else vier Science Ltd. All rights reserved.