Richard F. Geary Naila Rahman Rajeev Raman Venkatesh Raman A Simple Optimal Representation for Balanced Parentheses. 159-172 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3109&spage=159 2004 conf/cpm/2004 CPM db/conf/cpm/cpm2004.html#GearyRRR04