Lady Marianne E. Polinga and  Candy C. Mercado and  Camilo A. Polinga,  Formation and Evaluation of Lahar/HDPE Hybrid Composite as a Structural Material for Household Biogas Digester.   journal   = {International Journal of Materials and Metallurgical Engineering}, [online]. World Academy of Science, Engineering and Technology.
    July 2013, vol. 79(7). 487 - 490
    [viewed 08 December 2019]. Available from: https://publications.waset.org/pdf/16251.