@article{Du2007DIFFUSEIE,
  title={Diffuse Interface Energies Capturing the Euler Number: Relaxation and Renomalization},
  author={Qiang Du and Chun Liu and Rolf Ryham and Xiaoqiang Wang},
  journal={Communications in Mathematical Sciences},
  year={2007},
  volume={5},
  pages={233-242}
}