Z. Asadgol and  A. Nadali and  H. Arfaeinia and  M. Khalifeh Gholi and  R. Fateh and  M. Fahiminia,  Evaluation of Negative Air Ions in Bioaerosol Removal: Indoor Concentration of Airborne Bacterial and Fungal in Residential Building in Qom City, Iran.   journal   = {International Journal of Environmental and Ecological Engineering}, [online]. World Academy of Science, Engineering and Technology.
    February 2018, vol. 136(4). 300 - 311
    [viewed 12 July 2020]. Available from: https://publications.waset.org/pdf/10008747.