RT Journal Article SR Electronic T1 Tree Quality JF Arboriculture & Urban Forestry (AUF) FD International Society of Arboriculture SP 316 OP 318 DO 10.48044/jauf.1990.068 VO 16 IS 12 A1 Vollbrecht, Klaus YR 1990 UL http://auf.isa-arbor.com/content/16/12/316.abstract AB