@article{05657109,
title = {Homogeneous Lorentzian 3-manifolds with a parallel null vector field.},
journal = {Balkan Journal of Geometry and its Applications (BJGA)},
volume = {14},
year = {2009},
pages = {11-20},
zbl = {1186.53079},
language = {en},
url = {http://dml.mathdoc.fr/item/05657109}
}
Batat, W.; Calvaruso, G.; De Leo, B. Homogeneous Lorentzian 3-manifolds with a parallel null vector field.. Balkan Journal of Geometry and its Applications (BJGA), Tome 14 (2009) pp. 11-20. http://gdmltest.u-ga.fr/item/05657109/