中国科学院数学与系统科学研究院期刊网
AMS
A Variation of a Conjecture Due to Erdos and Sos
Jian Hua YIN, Jiong Sheng LI
Acta Mathematica Sinica . 2009, (5): 795 -802 .  DOI: 10.1007/s10114-009-7260-2