Industrial Gear Resources
Magazine
http://www.geartechnology.com
http://www.indmacdig.com
Book
http://www.industrialpress.com/
http://www.crcpress.com/shopping_cart/products/product_detail.asp?sku=TX62189&parent_id=&pc=
Industrial Gear Related Articles
http://www.machinerylubrication.com/article_detail.asp?articleid=417&relatedbookgroup=Lubrication
http://science.howstuffworks.com/gear-ratio.htm
http://www.grc.nasa.gov/WWW/RT/RT2000/5000/5950hardschuh.html