@misc{indiciae9d7edbf25198,
  title = {Optical sum rules for inhomogeneous electron systems.},
  author = {K Sturm},
  year = {1995},
  doi = {10.1103/physrevb.52.8028},
  url = {https://pubmed.ncbi.nlm.nih.gov/9979800/},
  note = {Source identifier: 9979800}
}