Electronic Journal of Differential Equations,
Vol. 2007(2007), No. 168, pp. 1-10.

Title: Periodicity in a delayed  ratio-dependent
       predator-prey system with exploited term

Authors: Zhijun Zeng (Chinese Academy of Sciences, Beijing,  China)
         Li Zhai     (Southwest Univ., Chongqing 400715, China)

Abstract: 
 With the help of the coincidence degree and the related
 continuation theorem, we explore the existence of at least two
 periodic solutions of a delayed ratio-dependent predator-prey
 system with exploited term. Some easily verifiable sufficient
 criteria are established for the existence of at least two
 positive periodic solutions.
  
Submitted December 2, 2006. Published December 03, 2007.
Math Subject Classifications: 34K45, 34K13, 92D25.
Key Words: Ratio-dependent predator-prey system;
           periodic solutions; coincidence degree.