IMBA's Sustainable Trail Building Overview
IMBA's Guide to Building Sweet Singletrack. The book costs $40 and is a great investment, but we'll loan you our copy for a bit if you want to give it a read. Just email us at firstname.lastname@example.org.
IMBA's Trail Building Class on Video (9 part series). If you watch the videos and use IMBA's Guide to Building Sweet Singletrack (see above) as a reference, you will get the same information provided in the IMBA/Subaru Trail Building Class.