Comrie, B. (1976). Aspect: An introduction to the study of verbal aspect and related problems. Cambridge; New York: Cambridge University Press. Frawley, W. (1992). Linguistic semantics. Hillsdale, NJ: Lawrence Erlbaum Associates. Kabakciev, K. (2000). Aspect in English: a "common-sense" view of the interplay between verbal and nominal referents (Studies in Linguistics and Philosophy). Springer. Retrieved 2016-05-18.
Comrie B (1976) Aspect An introduction to the study of verbal aspect and related problems Cambridge; New York Cambridge University Press Frawley W (1992) Linguistic semantics Hillsdale NJ Lawrence Erlbaum Associates Kabakciev K (2000) Aspect in English a "common-sense" view of the interplay between verbal and nominal referents (Studies in Linguistics and Philosophy) Springer Retrieved 2016-05-18