Oscillatory criteria for the second order linear functional - differential equations with locally integrable coefficients

The Riccati equation method is used to establish some oscillatory criteria for the second order linear functional - differential equations of multiple terms with locally integrable coefficients. An interval oscillation criterion for the second order linear functional - differential equations is proved. We have obtained a generalization of an oscillation theorem of L. Berezanski and E. Braverman, a generalization of the well known Fite’s oscillation criterion and a new global solvability criterion for the second order linear functional - differential equations with advanced and retarded arguments.