“…Then there exists a Riemannian submersion Π : N → M 2 (κ), where M 2 (κ) is a 2-dimensional simply connected space form of constant curvature κ, with totally geodesic fibers and there exists a unit Killing field ξ on N which is vertical with respect to Π. We will assume that N is oriented, and then we can define a vectorial product ∧, such that if {e 1 , e 2 } are linearly independent vectors at a point p, then {e 1 , e 2 , e 1 ∧ e 2 } is the orientation at p. If∇ denotes the Riemannian connection on N , the properties of ξ imply (see [4]) that for any vector field V ,…”