# Urmila Balasubramaniyam, Llionel S. Zisengwe, Niccoló Meriggi, Eric Buysman, Biogas production in climates with long cold winters, Wageningen, May 2008.
# Urmila Balasubramaniyam, Llionel S. Zisengwe, Niccoló Meriggi, Eric Buysman, Biogas production in climates with long cold winters, Wageningen, May 2008.