Sara Barati and  Karim Ivaz,  Variational Iteration Method for Solving Systems of Linear Delay Differential Equations.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    August 2012, vol. 68(8). 964 - 967
    [viewed 23 April 2024]. Available from: https://publications.waset.org/pdf/2307.