Inside the Human Body http://lung.ca/children/grades4_6/respiratory/index.html
Lung 101 http://www.lung.ca/lung101-renseignez/respiratory-respiratoire/how-comment/index_e.php
Welcome to the Respiratory System http://library.thinkquest.org/5777/resp1.htm?tqskip=1
Your Respiratory System http://yucky.discovery.com/flash/body/pg000138.html
How Your Lungs Work http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=40743