4Wen-tsun Wu. Selected works of Wen Tsun Wu[C]. World Scientific, 2008.
5Whitney H. Moscow 1935 : Topology Moving Toward America[ A]. Duren P L (Eds). A Century of MathemAtics in America[ M] , Part Ⅰ. Amer. Math,1985. 96-117.
6Tait P G. On the colouring of maps[J]. Proc. Roy. Soc. Edinb, 1878-1880, 10:501-503.
7Appel K, Haken W. Every Planar Map is Four Colorable, Part Ⅰ , Ⅱ [J]. Illinois J. Math, 1977, 21:429-567.
8Whiney H. The Coloring of Graphs[J]. Proc. Nat. Acad. Sci. USA, 1931, 17:122-125.
9Whitney H. Non-separable and Planar Graphs[J]. Proc. Nat. Acad. Sci. USA, 1931, 17:125-127.
10Whitney H. A Theorem on Graphs[J]. Annals of Math, 1931, 32 (2) :378-390.