@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/