General Rotational Surfaces in Pseudo-Euclidean 4-Space with Neutral   Metric
  We define general rotational surfaces of elliptic and hyperbolic type in the pseudo-Euclidean 4-space with neutral metric which are analogous to the general rotational surfaces of C. Moore in the Euclidean 4-space. We study Lorentz general rotational surfaces with plane meridian curves and give the complete classification of minimal general rotational surfaces of elliptic and hyperbolic type, general rotational surfaces with parallel normalized mean curvature vector field, flat general rotational surfaces, and general rotational surfaces with flat normal connection. 
Yana Aleksieva, Velichka Milousheva, Nurettin Cenk Turgay
math.DG