Book
Johnson, Gary R. Stem girdling roots : the underground epidemic killing our trees / by Gary Johnson, Dennis Fallon. [St. Paul, Minn.] : University of Minnesota : USDA Forest Service, Northeastern Area ; [Minneapolis, Minn.] : Xcel Energy, [2007].
Journal
Gilman, Edward F.; Harchick, Chris; Paz, Maria. Planting Depth Affects Root Form of Three Shade Tree Cultivars in Containers. Arboriculture & Urban Forestry, May2010, Vol. 36 Issue 3, p132-139
