Fuchs, Martín, and Marí­a Mercedes Piñango. 2019. “Explaining the Forces Underpinning Grammaticalization Paths: The Progressive-to-Imperfective Shift in Three Varieties of Spanish”. Proceedings of the Linguistic Society of America 4 (1): 6:1–11. https://doi.org/10.3765/plsa.v4i1.4491.