[16] Al Said, Hamid M. 2010. Design and building of biogas digester for organic materials gained from solid waste. Master of Science thesis. An najah national university, Nablus- Palestine. 131 pages.
[17] Amjid, Syed, Bilal, Muhammad and Hossain, Atlaf. 2011. Biogas, renewable energy resource for Pakistan. Renewable and Sustainable Energy Reviews. 15(6): 2833-2837.
[18] Babel, S.; Pecharaply, A.; Sae-Tang, J., (2009). Anaerobic digestion of sewage and brewery sludge for biogas production and land application. Int. J. Environ. Sci. Tech.,6 (1), 131-140 (10 pages).
[19] Buekens, A. 2005. Energy Recovery from Residual Waste by Means of Anaerobic Digestion Technologies. The Future of Residual Waste Management in Europe Conference.
[20] Juntarasiri, P., Nijsunkij, S., Buatick T., Jamkrajang, E., Wacharawichanant, S., 2011. Enhancing Biogas Production from Padauk Angsana Leave and Wastewater Feedstock through Alkaline and Enzyme Pretreatment, Energy Procedia, Vol. 9 207– 215.
[21] Khandelwal K, Mahdi S, Biogas Technology: A Practical Handbook, CRC Press. India. (2001).
[22] Pound, B., F. Done and T. R. Preston. 1981. Biogas production from mixtures of cattle slurry and pressed sugar cane stalk, with and without urea. Tropical animal production. 16: 345 -351.
[23] Saev, M., Koumanova1, B. and Simeonov, I. V. 2009. Anaerobic co-digestion of wasted tomatoes and cattle dung for biogas production. J. Uni. Chemical Technol. Metallurg. 44(1): 55-60.
[24] Sihuang, X. 2012. Evaluation of biogas production from anaerobic digestion of pig manure and grass silage. Ph. D. Thesis. Civil Engineering, National University of Ireland, Galway.
[25] Yadvika, Santosh, Sreekrishnan, T. R., Kohli, S., Rana, V., (2004). "Enhancement of Biogas Production from Solid Substrates Using Different Techniques- A review." Bio-resource. Technol., 95: 1-10
[26] Zhang R, El-Mashad H.M., Hartman K, Wang F, Liu G, Choate, Gamble P. (2007) Characterization of food waste as feedstock for anaerobic digestion. Bio-resource Technology 98: 929-925.
[27] Zhong, w., zh. Zhang, w. qiao, p. Fu, and M. Liu. 2011. Comparison of chemical and biological pretreatment of corn straw for biogas production by anaerobic digestion. Renewable energy. 36: 1875-1879.