1. Petersson A, Wellinger A. Biogas upgrading technologies - developments and innovations. IEA bioenergy, task 37 - energy from biogas and landfill gas; 2009.
2. Selection of appropriate biogas upgrading technology-a review of biogas cleaning, upgrading and utilisation;Sun;Renew Sustain Energy Rev,2015
3. Techniques for transformation of biogas to biomethane;Ryckebosch;Biomass Bioenergy,2011
4. Injection of biogas, SNG and hydrogen into the gas grid;Graf;gwf-Gas Erdgas,2011
5. Persson M, Jönsson O, Wellinger A. Biogas upgrading to vehicle fuel standard and grid injection. IEA bioenergy, task 37 - energy from biogas and landfill gas; 2006.