Based on Mawhin's coincidence degree theory, sufficient conditions are obtained for the existence of at least two positive periodic solutions for a plant-hare model with toxin-determined functional response (nonmonotone). Some new technique is used in this paper, because standard arguments in the literature are not applicable.
Yongfei Gao. P. J. Y. Wong. Y. H. Xia. Xiaoqing Yuan. "Multiple Periodic Solutions of a Nonautonomous Plant-Hare Model." Abstr. Appl. Anal. 2014 (SI01) 1 - 7, 2014. https://doi.org/10.1155/2014/130856