1. Aguado, Gerardo (1988). Appraisal of the morpho-syntactic competence in a 2;5 month old child. Infancia y Aprendizaje 43: 73-95.
2. Austin, Jennifer, Maria Blume, Barbara Lust, Zelmira Nu ez del Prado, David Parkinson and Reyna Proman (1996). Current challenges to the parameter-setting paradigm: The pro-drop parameter. In Proceedings of the Groningen Assembly on Language Acquisition held at the University of Groningen, 7-9 September 1995, C. Koster and F. Wijnen (eds.), 87-96. Groningen: Centre for Language and Cognition.
3. Austin, Jennifer, Maria Blume, David Parkinson, Zelmira Nu ez del Prado and Barbara Lust (1997). The Status of Pro-Drop in the Initial State: Results from New Analyses of Spanish.In Contemporary Perspectives on the Acquisition of Spanish. Volume I: Developing Grammars, A.T. Perez-Leroux and W.R. Glass (eds.), 37-54. Somerville, Mass.: Cascadilla Press.
4. Bel, Aurora (1998). Teoria ling istica i adquisicio del llenguatge. Analisi comparada dels trets morfologics en catala i en castella. Ph.D. dissertation. Universitat Autonoma de Barcelona, Barcelona.
5. (2001). The Projection of Aspect: A Key in the Acquisition of Finiteness? In Research on Child Language Acquisition. Proceedings of the 8th Conference of the International Association for the Study of Child Language, 1300-1316. Somerville/Massachusetts: Cascadilla Press.