Problems with one quarter

summary:In this paper two sequences of oscillation criteria for the self-adjoint second order differential equation $(r(t)u^{\prime }(t))^{\prime }+p(t)u(t)=0$ are derived. One of them deals with the case $\int ^{\infty }\frac{{\mathrm d}t}{r(t)}=\infty$, and the other with the case $\int ^{\infty }\frac{{\mathrm d}t}{r(t)}<\infty$