Yan Rongxin and  Sun Wei and  Li Weidan,  Research and Design on a Portable Intravehicular Ultrasonic Leak Detector for Manned Spacecraft.   journal   = {International Journal of Aerospace and Mechanical Engineering}, [online]. World Academy of Science, Engineering and Technology.
    April 2017, vol. 126(6). 1161 - 1166
    [viewed 23 October 2019]. Available from: https://publications.waset.org/pdf/10007176.