The definition of the Einstein 3-form Gα is motivated by means of the contracted 2nd Bianchi identity. This definition involves at first the complete curvature 2-form. The 1-form Lα is defined via Gα = L β ∧ (θβ ∧ θα) (here ⋆ is the Hodge-star, θα the coframe). It is equivalent to the Einstein 3-form and represents a certain contraction of the curvature 2-form. A variational formula of Salgado ...