中国科学院数学与系统科学研究院期刊网
The Carcterization for the Extreme Digraphs of the k~(th) Upper Generalized Exponents
Yan Ling SHAO(1),Yu Bin GAO(2)
Acta Mathematica Sinica, Chinese Series . 2000, (3): 427 -434 .  DOI: 10.12386/A2000sxxb0056