@article{JLT_2015_25_4_JLT_2015_25_4_a4,
     author = {G. Calvaruso and A. Zaeim},
     title = {Neutral {Metrics} on {Four-Dimensional} {Lie} {Groups}},
     journal = {Journal of Lie theory},
     pages = {1023--1044},
     year = {2015},
     volume = {25},
     number = {4},
     url = {http://geodesic.mathdoc.fr/item/JLT_2015_25_4_JLT_2015_25_4_a4/}
}