@article{GDZPPN002419785, title = {The Critical Points Theory for the Closed Geodesics Problem.}, journal = {Mathematische Zeitschrift}, volume = {154}, year = {1977}, pages = {231-246}, zbl = {0344.58013}, url = {http://dml.mathdoc.fr/item/GDZPPN002419785} }
Mercuri, Francesco. The Critical Points Theory for the Closed Geodesics Problem.. Mathematische Zeitschrift, Tome 154 (1977) pp. 231-246. http://gdmltest.u-ga.fr/item/GDZPPN002419785/