@phdthesis{Abdellatif2012,
  author    = {Ahmad Fouad Abdalwahab Abdellatif},
  title     = {On metric-affine gravitational theories with a Lagrangian quadratic in the curvature and the energy-momentum problem},
  journal    = {Ueber metrisch-affine Gravitationstheorien mit einem in der Kruemmung quadratischen Lagrangian und {\"u}ber das Energie-Impuls-Problem},
  url       = {https://nbn-resolving.org/urn:nbn:de:gbv:9-001172-2},
  year      = {2012},
  abstract  = {The geometric arena here is a smooth manifold of dimension n equipped with a Riemannian or pseudo-Riemannian metric and an affine connection. Field theories following from a variational principle are considered on this basis. In this context, all invariants which are quadratic in the curvature are determined. The work derives several manifestly covariant formulas for the Euler-Lagrange derivatives or the field equations. Some of these field theories can be interpreted as gravitational theories alternatively to Einstein´s general relativity theory. The work also touches the difficult problem to define and to calculate energy and momentum of a gravitational field.},
  language  = {en}
}