Barakat, H. M., M. A. Ismail, and S. D. Ravana. “Utilization Of Cross-Terms To Enhance The Language Model For Information Retrieval”. Malaysian Journal of Computer Science, vol. 26, no. 3, Sept. 2013, pp. 196-10, http://jice.um.edu.my/index.php/MJCS/article/view/6772.