Journal of Geometry and Physics
Journal of Geometry and Physics > 2002 > 41 > 3 > 196-207
Journal of Geometry and Physics > 2002 > 41 > 3 > 258-273
Journal of Geometry and Physics > 2002 > 41 > 3 > 196-207
Journal of Geometry and Physics > 2002 > 41 > 3 > 258-273