http://es.wikipedia.org/wiki/Cr%C3%A1teres_de_R%C3%ADo_Cuarto
http://www.science-frontiers.com/sf080/sf080g11.htm
http://www.arm.ac.uk/impact-hazard/
http://www.nightskyhunter.com/Astro%20Links.html
http://www.star-bits.com/impact-craters.htm
http://www.uwgb.edu/dutchs/planets/impact4.htm
http://www.xs4all.nl/~carlkop/kraters.html
http://www.imo.net/bib/mticra0.html
http://www.lpi.usra.edu/meetings/programs/msattiiwa.txt
http://www.zetatalk.com/theword/tworx087.htm
http://www.unb.ca/passc/ImpactDatabase/SAm.html
http://www.campodelcielo.com.ar/index.html