Journal of Geometry and Physics
Journal of Geometry and Physics > 2012 > 62 > 2 > 352-360
Journal of Geometry and Physics > 2012 > 62 > 7 > 1639-1651
Journal of Geometry and Physics > 2012 > 62 > 2 > 352-360
Journal of Geometry and Physics > 2012 > 62 > 7 > 1639-1651