@article{GDZPPN002355485, title = {Non-hyperbolic closed geodesics.}, journal = {Mathematica Scandinavica}, volume = {44}, year = {1979}, pages = {135-148}, zbl = {0414.53037}, url = {http://dml.mathdoc.fr/item/GDZPPN002355485} }
Thorbergsson, Gudlaugur. Non-hyperbolic closed geodesics.. Mathematica Scandinavica, Tome 44 (1979) pp. 135-148. http://gdmltest.u-ga.fr/item/GDZPPN002355485/