@article{KJM_2017_41_2_a6,
     author = {A. A. Shaikh and Y. Matsuyama},
     title = {Curvature {Properties} of {Some} {4-Dimensional} {Semi-Riemannian} {Metrics}},
     journal = {Kragujevac Journal of Mathematics},
     pages = {259 },
     publisher = {mathdoc},
     volume = {41},
     number = {2},
     year = {2017},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/KJM_2017_41_2_a6/}
}