1. Akkoc, H. (2008). Pre-service mathematics teachers’ concept images of radian. International Journal of Mathematical Education in Science and Technology, 39(7), 857-878. https://doi.org/10.1080/00207390802054458.
2. Allen, H. D. (1977). The teaching of trigonometry in the United States and Canada: A consideration of elementary course content and approach and factors influencing change, 1890-1970 (Unpublished doctoral dissertation), The State University of New Jersey, New Brunswick, NJ.
3. Biehler, R. (2005). Reconstruction of Meaning as a Didactical Task: The Concept of Function as an Example. In Kilpatrick J., Hoyles C., Skovsmose O., Valero P. (Eds), Meaning in Mathematics Education. Mathematics Education Library (vol 37, pp. 61-81). New York, NY: Springer. https://doi.org/10.1007/0-387-24040-3_5.
4. Brown, S.A. (2005). The trigonometric connections: Students’ understanding of sine and cosine (Unpublished doctoral dissertation), Illinois State University, Illinois, IL.
5. Bunge, M. (2008). Tratado de Filosofía. Semántica I, Sentido y referencia. Barcelona, Spain: Gedisa Editorial.