Webelhuth, Gert, and Olivier Bonami. Syntactic haplology and the Dutch proform "er" In Proceedings of the 26th International Conference on Head-Driven Phrase Structure Grammar, University of Bucharest, Edited by Stefan Müller and Petya Osenova. Stanford, CA: CSLI Publications, 2019.

Nivre, Joakim, Mitchell Abrams, ?eljko Agi?, Lars Ahrenberg, Lene Antonsen, Maria Jesus Aranzabe, Gashaw Arutie, Masayuki Asahara, Luma Ateyah, Mohammed Attia et al. Universal Dependencies 2.2., 2018.

Nivre, Joakim, ?eljko Agi?, Lars Ahrenberg, Lene Antonsen, Maria Jesus Aranzabe, Masayuki Asahara, Luma Ateyah, Mohammed Attia, Aitziber Atutxa, Liesbeth Augustinus et al. Universal Dependencies 2.1., 2017.