@article{SIGMA_2012_8_a31,
     author = {Laurent Freidel and Simone Speziale},
     title = {On the relations between gravity and {BF} theories},
     journal = {Symmetry, integrability and geometry: methods and applications},
     year = {2012},
     volume = {8},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SIGMA_2012_8_a31/}
}