WASET
    Anqi Wang and  Linye Zhang,  A Study of the Assistant Application for Tourists Taking Metros.   journal   = {International Journal of Computer and Information Engineering}, [online]. World Academy of Science, Engineering and Technology.
    January 2019, vol. 146(2). 55 - 64
    [viewed 08 May 2024]. Available from: https://publications.waset.org/pdf/10010036.