Measure link https://www.irena.org/-/media/files/irena/agency/publication/2017/mar/irena_bio… https://www.theccc.org.uk/wp-content/uploads/2013/12/1785b-CCC_TechRep_Singles_… https://afdc.energy.gov/vehicles/natural_gas.html http://www.civitas.eu/sites/default/files/20140724_webinarufl_noon.pdf http://www.rms.nsw.gov.au/documents/about/environment/air/hybrid-technology-cas…