1. Foundations of Language: Brain, Meaning, Grammar, Evolution;Jackendoff,2003
2. The Cambridge Handbook of Linguistic Typology;Aikhenvald,2017
3. Some universals of grammar with particular reference to the order of meaningful elements;Greenberg;Universals Lang.,1963
4. Human Behaviour and the Principle of Least Effort;Zipf,1949
5. The origin of speech;Hockett;Sci. Am.,1960