Seiichiro Tani Hirotada Kobayashi Keiji Matsumoto Exact Quantum Algorithms for the Leader Election Problem. 581-592 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3404&spage=581 2005 conf/stacs/2005 STACS db/conf/stacs/stacs2005.html#TaniKM05