Khalil, Tariq M. , Stewart S. Higgins, Pius M. Ndegwa, Craig S. Frear, Claudio O. Stöckle. Journal of Environmental Management, Volume 182, 1 November 2016, Pages 230-237, ISSN 0301-479.
Anaerobic Digestion Systems: Integrating emerging technologies to improve environmental and economic impact
C. Frear, C.Kruger, H. Collins, M. Garcia-Perez, C. Stockle, R. Shumway, G. Astill, T. Ewing, N. Kennedy, T. Khalil, and G. Yorgey. July 2013. Academic Poster.