Full paper in PDF:
$% J. Lafuente López, A geodesic completeness theorem for locally symmetric Lorentz
manifolds, Rev. Mat. Univ. Complut. Madrid 1 (1988), no. 1, 2, 3, 101–110.%$
A Geodesic Completeness Theorem for Locally Symmetric Lorentz Manifolds
1980 Mathematics Subject Classification (1985 revision): 53C50.