@article{HermannHumbert2016,
  author    = {Andreas Hermann and Emmanuel Humbert},
  title     = {About the mass of certain second order elliptic operators},
  journal   = {Advances in mathematics},
  volume    = {294},
  pages     = {596 -- 633},
  doi       = {10.1016/j.aim.2016.03.008},
  year      = {2016},
}