@article{1103815047, author = {Pechlaner, E. and Sexl, R.}, title = {On quadratic Lagrangians in general relativity}, journal = {Comm. Math. Phys.}, volume = {1}, number = {5}, year = {1966}, pages = { 165-175}, language = {en}, url = {http://dml.mathdoc.fr/item/1103815047} }
Pechlaner, E.; Sexl, R. On quadratic Lagrangians in general relativity. Comm. Math. Phys., Tome 1 (1966) no. 5, pp. 165-175. http://gdmltest.u-ga.fr/item/1103815047/