1. [Deacon 1997] Deacon, T.W.: The Symbolic Species: The Co-evolution of Language and the Brain, Norton, 1978.
2. [Halliday 1978] Halliday, M.A.K.: Language as Social Semiotic: the Social Interpretation of Language and Meanings, Edward Arnold, 1978.
3. [Halliday 1999] Halliday, M.A.K. and C. Matthiessen: Constructing Experience Through Meaning: A Language Based Approach to Cognition, Cassell Academic, 1999.
4. [FIPA] http://www.fipa.org