@article{MM2_1980__31_154708,
     author = {P. Ehrlich and Carmen Chicone},
     title = {Line {Integration} of {Ricci} {Curvature} and {Conjugate} {Points} in {Lorentzian} and {Riemannian} {Manifolds.}},
     journal = {Manuscripta mathematica},
     pages = {297--316},
     publisher = {mathdoc},
     volume = {31},
     year = {1980},
     zbl = {0436.53043},
     url = {http://geodesic.mathdoc.fr/item/MM2_1980__31_154708/}
}