1. Yongquan Li, Andrew Lim, Wee-Chong Oon, Hu Qin, Dejian Tu, The Tree Representation for the Pickup and Delivery Traveling Salesman Problem with LIFO Loading, European Journal of Operational Research (EJOR), Vol 212, Issue 3,2011.2. Yongquan Li, Kaijie Zhu, ”Information acquisition in new product introduction”, European Journal of Operational Research (EJOR), Vol 198, Issue 2, 2009.