@article{10_4153_CJM_2011_091_1,
     author = {Calvaruso, Giovanni and Fino, Anna},
     title = {Ricci {Solitons} and {Geometry} of {Four-dimensional} {Non-reductive} {Homogeneous} {Spaces}},
     journal = {Canadian journal of mathematics},
     pages = {778--804},
     year = {2012},
     volume = {64},
     number = {4},
     doi = {10.4153/CJM-2011-091-1},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-2011-091-1/}
}