  The 2-parameter family of certain homogeneous Lorentzian 3-manifolds which
includes Minkowski 3-space and anti-de Sitter 3-space is considered. Each
homogeneous Lorentzian 3-manifold in the 2-parameter family has a solvable Lie
group structure with left invariant metric. A generalized integral
representation formula which is the unification of representation formulas for
maximal spacelike surfaces in those homogeneous Lorentzian 3-manifolds is
obtained. The normal Gau{\ss} map of maximal spacelike surfaces in those
homogeneous Lorentzian 3-manifolds and its harmonicity are discussed.
