US Forest Service General Tech. Report NE-82; 1983; 167 pages
To view and download the official document (see Tree Defects -Part A, B, C) : http://www.fs.fed.us/ne/newtown_square/publications/popular-publications.shtml
However, this html version has higher quality images.
Tree Defects: A Photo Guide
Alex L. Shigo
US Forest Service General Tech. Report NE-82; 1983; 167 pages
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