Brocardo, Maria Teresa. “’Ser Teudo De responder’ or ’ter De responder’: On the Emergence of Deontic Uses of ’ter De (que)’ + INF in Portuguese”. Journal of the Portuguese Linguistics Association, no. 7, Nov. 2020, pp. 55-68, doi:10.26334/2183-9077/rapln7ano2020a4.