Morgan, C. (1996). “The Language of Mathematics”: Towards a critical analysis of mathematics texts. For the Learning of Mathematics, 16(3), 2–10. doi:10.2307/40248208
Also Morgan, C. (2005). Word, definitions and concepts in discourses of mathematics, teaching and learning. Language and Education, 19(2), 102–116.
I am not sure what education level you are referring to - primary, secondary, tertiary. Some colleagues and I did some work a few years ago on teacher education in mathematics and approached its teaching using a metaphor of "Mathematics as a Language". I have provided the publication details below - but am not sure whether or not this is the angle you are taking. Regards, Kevin
Larkin, K., Jamieson-Proctor, R., & Finger, G. (2012). TPACK and Pre-Service Teacher Mathematics Education: Defining a Signature Pedagogy for Mathematics Education Using ICT and Based on the Metaphor "Mathematics Is a Language". Computers in the Schools, 29(1-2), 207.
Thank you to everybody, I'm I am pleasantly surprised: I've got much more references that I could expect.
We are working on mathematical modelling with high school student. Often, these students generate very interesting models involving big ideas but they are not able to represent them using formal language. We are trying to study the way they represent these ideas and then appeared this need to know more about different languages in mathematics.