binding. Studies in Generative Grammar 9. Dordrecht: Foris. Chomsky, Noam 1982. Concepts and Consequences of the Theory of Government and Binding. The MIT Press, Cambridge, Mass. D’Alessandro, Roberta. 2014. The Null Subject Parameter: Where are we and where are we headed? Ms. Leiden University Centre for Linguistics. Gilligan, Gary Martin. 1987. “A crosslinguistic approach to prodrop parameter.” PhD. dissertation, University of Southern California, Los Angeles. Holmberg, Anders. 2005. “Is there a little pro? Evidence from Finnish.” Linguistic Inquiry 36:533-564. Jaeggli, Oswaldo and Ken Safir 1987 (eds) The null subject parameter. Dordrecht: Kluwer. Kučerová, Ivona 2014. “The Syntax of Null Subjects.” Syntax 17:2, 132167. Perlmutter, David 1971. Deep and surface constraints in syntax. New York: Holt, Rinehart and Winston. Rizzi, Luigi 1986. 'Null Objects in Italian and the Theory of pro' Linguistic Inquiry 17:1986. pp. 501-557. Rizzi, Luigi 1982. Issues in Italian Syntax, Foris Publications, Dordrecht. Vikner, Sten. 1995. Verb Movement and Expletive Subjects in the Germanic Languages, Oxford University Press, Oxford. Zanuttini, Raffaella. 2008. Microcomparative syntax in English verbal agreement. Talk at NELS 39, November 2008. External links List of languages including pro-drop (PD) or non-pro-drop (NPD) status, which is usually related to null-subject or non-null-subject status. Linguistic typology