Rybach, Ladislaus (September 2007), "Geothermal Sustainability"(PDF), Geo-Heat Centre Quarterly Bulletin, Klamath Falls, Oregon: Oregon Institute of Technology, vol. 28, no. 3, pp. 2–7, ISSN0276-1084, archived from the original(PDF) on 17 February 2012, retrieved 25 April 2013
Rybach, Ladislaus (September 2007), "Geothermal Sustainability"(PDF), Geo-Heat Centre Quarterly Bulletin, Klamath Falls, Oregon: Oregon Institute of Technology, vol. 28, no. 3, pp. 2–7, ISSN0276-1084, archived from the original(PDF) on 17 February 2012, retrieved 25 April 2013
worldcat.org
Rybach, Ladislaus (September 2007), "Geothermal Sustainability"(PDF), Geo-Heat Centre Quarterly Bulletin, Klamath Falls, Oregon: Oregon Institute of Technology, vol. 28, no. 3, pp. 2–7, ISSN0276-1084, archived from the original(PDF) on 17 February 2012, retrieved 25 April 2013