Chenxi Yang and  Zhouhong Li,  Permanence and Almost Periodic Solutions to an Epidemic Model with Delay and Feedback Control.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    March 2014, vol. 85(1). 240 - 246
    [viewed 25 April 2024]. Available from: https://publications.waset.org/pdf/9997884.