Raymond Yeo K. W. and  P. Y. Lim and  Farrah Wong,  Design and Development of an Innovative Advertisement Display with Flipping Mechanism.   journal   = {International Journal of Electrical and Computer Engineering}, [online]. World Academy of Science, Engineering and Technology.
    August 2014, vol. 88(4). 720 - 725
    [viewed 25 April 2024]. Available from: https://publications.waset.org/pdf/9999285.