1. Liu, H. T., Xu, C. S., and Liang J. Y. 2017. Dependency distance: A new perspective on syntactic patterns in natural languages. Physics of Life Reviews, 171--193.
2. Roland, H. 2014. Foundations of Computational Linguistics (Third Edition). Springer-Verlag, Heidelberg.
3. Cook, G. 2012. Applied Linguistics. Shanghai Foreign Language Education Press, Shanghai.
4. Feng, Z. W. 2001. Fundamentals of Computational Linguistics. The Commercial Press, Beijing.
5. Jurafsky, D., Martin, J. H. 2008. Speech and Language Processing (Second Edition). Prentice Hall, Englewood.