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:
Gear geometry data is available from PIC Design Inc. which is now part of RBC Bearings at the link:
http://pic-designcatalog.com/Images/pdfcat/section_12.pdf
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Stock Drive Products provides an on-line Handbook of Gears at the website:
http://www.sdp-si.com/products/Gears/Index.php
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The Gleason Gear has a lot of useful information:
The American Gear Manufacturers Association provides standards for sale on-line at the site:
https://www.agma.org/standards/.
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