ThomasNet provides a link to a useful white paper on Timing Belt Theory by Gates-Mectrol:

http://www.thomasnet.com/white-papers/abstract/101106/timing-belt-theory.html

Geometric data on timing belt drives can found in the catalog linked to Gates-Mectrol home page:

http://www.gatesmectrol.com/

Gear geometry data is available from PIC Design Inc. which is now part of RBC Bearings at the link:

http://www.pic-design.com/static/PDF/Catalog%2045.0.pdf

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Stock Drive Products provides an on-line Handbook of Gears at the website:

http://www.sdp-si.com/D190/D190cat.htm

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The Gleason Gear Encyclopedia is available for sale at the site:

http://www.quikey-c.com/gleason/SKUDetailsGLEAFGL6000.Asp

The American Gear Manufacturers Association provides standards for sale on-line at the site:

http://www.agma.org/Content/NavigationMenu/Publications/TechnicalPublicationsStandards/AGMAStandardsInformationSheets/default.

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