@article{10084,
  author = {I. Percival},
  title = {Variational principles for the invariant toroids of classical dynamics},
  year = {1974},
  journal = {Journal of Physics A: Mathematical, Nuclear and General},
  volume = {7},
  pages = {794-802},
  month = {Jan-05-1974},
  issn = {0301-0015},
  url = {http://stacks.iop.org/0301-0015/7/i=7/a=005?key=crossref.bc6b51a39f99c5c168c60bdf05340891},
  doi = {10.1088/0305-4470/7/7/005},
}