WASET
    Bogdan Bogdanov and  Irena Markovska and  Yancho Hristov and  Dimitar Georgiev,  Lightweight Materials Obtained by Utilization of Agricultural Waste.   journal   = {International Journal of Materials and Metallurgical Engineering}, [online]. World Academy of Science, Engineering and Technology.
    April 2012, vol. 64(4). 332 - 335
    [viewed 11 May 2024]. Available from: https://publications.waset.org/pdf/12413.