J. . Ahamed, M. . Raiyan, M. S. . Hossain, M. . Rahman, and B. . Salam, “Production of biogas from anaerobic digestion of poultry droppings and domestic waste using catalytic effect of silica gel”, Int. J. Automot. Mech. Eng., vol. 13, no. 2, pp. 3503–3517, Dec. 2022, doi: 10.15282/ijame.13.2.2016.17.0289 3503 .