Anton Batliner Anke Feldhaus Stefan Geißler Andreas Kießling Tibor Kiss Ralf Kompe Elmar Nöth Integrating Syntactic and Prosodic Information for the Efficient Detection of Empty Categories. 71-76 1996 COLING http://acl.ldc.upenn.edu/C/C96/C96-1014.pdf db/conf/coling/coling1996.html#BatlinerFGKKKN96