Jianping Li Weidong Li Tongquan Zhang Zhongxu Zhang The subdivision-constrained minimum spanning tree problem. 877-885 2009 410 Theor. Comput. Sci. 8-10 http://dx.doi.org/10.1016/j.tcs.2008.12.038 db/journals/tcs/tcs410.html#LiLZZ09