Zhouhong Li and  Jiming Yang,  Multiple Positive Periodic Solutions to a Periodic Predator-Prey-Chain Model with Harvesting Terms.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    August 2011, vol. 56(8). 1292 - 1297
    [viewed 26 April 2024]. Available from: https://publications.waset.org/pdf/1330.