Hauer، Richard J.؛ Dawson، Jeffrey O.؛ Werner، Les P. (2006). Trees and Ice Storms - The Development of Ice Storm-Resistant Urban Tree Populations(PDF) (ط. 2). College of Natural Resources, University of Wisconsin–Stevens Point, and the Department of Natural Resources and Environmental Sciences and the Office of Continuing Education, University of Illinois at Urbana-Champaign. مؤرشف من الأصل(PDF) في 2009-03-07.
Hauer، Richard J.؛ Dawson، Jeffrey O.؛ Werner، Les P. (2006). Trees and Ice Storms - The Development of Ice Storm-Resistant Urban Tree Populations(PDF) (ط. 2). College of Natural Resources, University of Wisconsin–Stevens Point, and the Department of Natural Resources and Environmental Sciences and the Office of Continuing Education, University of Illinois at Urbana-Champaign. مؤرشف من الأصل(PDF) في 2009-03-07.