@article{1250129367, author = {Smith, Hal L.}, title = {Periodic solutions of an epidemic model with a threshold}, journal = {Rocky Mountain J. Math.}, volume = {9}, number = {4}, year = {1979}, pages = { 131-142}, language = {en}, url = {http://dml.mathdoc.fr/item/1250129367} }
Smith, Hal L. Periodic solutions of an epidemic model with a threshold. Rocky Mountain J. Math., Tome 9 (1979) no. 4, pp. 131-142. http://gdmltest.u-ga.fr/item/1250129367/