http://www.dentistry.com/articles/Benefits_of_Nitrous_Oxide.aspx

http://www.dentalfearcentral.org/laughing_gas.html

http://www.porterinstrument.com/dental_1.php

http://www.crosstimbersdental.com/nitrousoxide.html

http://www.wvdentalboard.org/NITROUS%20OXIDE%20GUIDELINES.pdf

http://www.cdc.gov/niosh/noxidalr.html

http://www.mynewsmile.com/dental/nitrous_oxide.htm

http://dentistry.about.com/od/dentalfactsfaqs/f/N2O.htm

http://www.softdental.com/houston_dentist/nitrous_oxide.html

http://www.aapd.org/publications/brochures/nitrous.asp