@article{GDZPPN002202077, title = {The periods of the Volterra-Lotka system.}, journal = {Journal f\"ur die reine und angewandte Mathematik}, volume = {346}, year = {1984}, pages = {129-138}, zbl = {0547.92011}, url = {http://dml.mathdoc.fr/item/GDZPPN002202077} }
Rothe, Franz. The periods of the Volterra-Lotka system.. Journal für die reine und angewandte Mathematik, Tome 346 (1984) pp. 129-138. http://gdmltest.u-ga.fr/item/GDZPPN002202077/