“…Recently, the estimates on the upper bound have been solved for the local indefinite Sturm-Liouville problem, i.e., K(x, t) = 0, w changes its sign on [0, 1] in (1.1) with self-adjoint boundary conditions in [14,21,31]. The estimates on the bounds of eigenvalues for the complex local Sturm-Liouville problems have been studied by the Rayleigh-Ritz method for w ≡ 1, q > 0 in [11] and for the general case in [12].…”