@article{PfaeffleStephan2012,
  author    = {Frank Pf{\"a}ffle and Christoph A. Stephan},
  title     = {On gravity, torsion and the spectral action principle},
  journal   = {Journal of functional analysis},
  volume    = {262},
  number    = {4},
  pages     = {1529 -- 1565},
  doi       = {10.1016/j.jfa.2011.11.013},
  year      = {2012},
}