@misc{indiciae3145a6408312,
  title = {Perturbation theory for Floquet eigenvalues in a zero-range potential.},
  author = {G Alvarez and B Sundaram},
  year = {1990},
  doi = {10.1103/physreva.42.452},
  url = {https://pubmed.ncbi.nlm.nih.gov/9903822/},
  note = {Source identifier: 9903822}
}