@article{Zhang.etal:2016,
  title = {Unified Expression of Rotational Hardening in Clay Plasticity},
  author={Zhang, Hao and Chen, Qiushi and Chen, Jinjian and Wang, Jianhua},
  journal = {International Journal of Geomechanics},
  volume = {16},
  number = {6},
  pages = {06016004},
  doi = {10.1061/(ASCE)GM.1943-5622.0000647},
  year = {2016},
  publisher={American Society of Civil Engineers}
}