http://www.jri.co.jp/MediaLibrary/file/report/researchfocus/pdf/6355.pdf

http://oilgas-info.jogmec.go.jp/report_pdf.pl?pdf=1210_out_c_gas_as_automotive_fuel_by_shale_revolution.pdf&id=4766

http://www.murc.jp/politics_c1/search_now/2012/10/sn_121003.html

http://criepi.denken.or.jp/jp/serc/denki/pdf/20121001.pdf

http://www.meti.go.jp/meti_lib/report/2011fy/E001537-1.pdf

http://www.okb-kri.jp/_userdata/pdf/report/147-2.pdf

http://www.pecj.or.jp/japanese/minireport/pdf/H24_2012/2012-021.pdf