Bibliography

Reference: http://www.nap.edu/openbook.php?record_id=1784&page=1 (extracted 28-02-2010)Authors:
Committee on Natural Disasters, Division of Natural Hazard Mitigation, National Research Council

http://www.smate.wwu.edu/teched/geology/vo-eruption2.html (extracted 28-02-2010) Photograph credit: U.S. Geological Survey.
http://www.geology.sdsu.edu/how_volcanoes_work/Nevado.html (extracted 28-02-2010)
http://en.wikipedia.org/wiki/Nevado_del_Ruiz#Eruption_and_lahars (extracted 28-02-2010)
http://news.bbc.co.uk/onthisday/hi/dates/stories/november/13/newsid_2539000/2539731.stm (extracted 28-02-2010)
http://www.geology.sdsu.edu/how_volcanoes_work/Variability.html (extracted 28-02-2010)
http://www.traveljournals.net/explore/colombia/map/m841843/nevado_del_ruiz.html (extracted 28-02-2010)
Pictures:
http://www.smate.wwu.edu/teched/geology/GeoHaz/vo-Eruption2/vo-eruption2-10.JP (extracted 28-02-2010) Photograph credit: U.S. Geological Survey.
http://www.geology.sdsu.edu/how_volcanoes_work/Variability.html (extracted 28-02-2010)
http://feww.wordpress.com/category/volcanoes/ (extracted 28-02-2010)[Source: USGS]