@misc{indiciae3632bfab7cbc,
  title = {Global invariants for variable-mass systems.},
  author = {James E Howard},
  year = {2006},
  doi = {10.1103/physrevlett.97.164302},
  url = {https://pubmed.ncbi.nlm.nih.gov/17155401/},
  note = {Source identifier: 17155401}
}