Walter G. Kropatsch Yll Haxhimusa Zygmunt Pizlo Integral Trees: Subtree Depth and Diameter. 77-87 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3322&spage=77 2004 conf/iwcia/2004 IWCIA db/conf/iwcia/iwcia2004.html#KropatschHP04