Kotek, Hadas and Michael Yoshitaka Erlewine, 2016. “Unifying definite and indefinite free relatives: Evidence from Mayan.”
Proceedings of NELS 46, volume 2, pages 241–254.

We investigate definite and indefinite free relatives in Chuj, a Mayan language of Guatemala. Indefinite free relatives in Chuj are equivalent in size to definite free relatives, contrary to a well-supported conjecture by Šimík (2011) that indefinite free relatives are always reduced clauses (specifically, modal existential wh-constructions). We show that the non-island status of indefinite free relatives is due to their being CPs without a DP layer; it is not the case that extraction out of relative clauses on indefinites can somehow proceed without island violations. We also present supporting evidence from two other Mayan languages, Yucatec Maya and Kaqchikel.