WASET
    Christoph Speer,  Rotor Concepts for the Counter Flow Heat Recovery Fan.   journal   = {International Journal of Civil and Environmental Engineering}, [online]. World Academy of Science, Engineering and Technology.
    March 2015, vol. 106(10). 1399 - 1402
    [viewed 25 April 2024]. Available from: https://publications.waset.org/pdf/10006781.