@ARTICLE{LeCAA2014,
  author={Zhang, Chenghui and Chang, Le and Zhang, Xianfu},
  journal={IEEE/CAA Journal of Automatica Sinica}, 
  title={Leader-follower consensus of upper-triangular nonlinear multi-agent systems}, 
  year={2014},
  volume={1},
  number={2},
  pages={210-217},
  doi={10.1109/JAS.2014.7004552}
}