W. Timothy Liu; Xiaosu Xie; Wenqing Tang (2006). "Monsoon, Orography, and Human Influence on Asian Rainfall"(PDF). Proceedings of the First International Symposium in Cloud-prone & Rainy Areas Remote Sensing (CARRS), Chinese University of Hong Kong. Archived from the original(PDF) on 2006-09-29. Retrieved 2010-01-04.
Humanitarian Bulletin Yemen Issue 5(PDF) (Report). United Nations Office for the Coordination of Humanitarian Affairs. 13 November 2015. Retrieved 2 February 2016 – via ReliefWeb.
W. Timothy Liu; Xiaosu Xie; Wenqing Tang (2006). "Monsoon, Orography, and Human Influence on Asian Rainfall"(PDF). Proceedings of the First International Symposium in Cloud-prone & Rainy Areas Remote Sensing (CARRS), Chinese University of Hong Kong. Archived from the original(PDF) on 2006-09-29. Retrieved 2010-01-04.