@misc{indiciae61b98503895c,
  title = {Frequency-domain instability criteria for time- varying and nonlinear systems.},
  author = {Brockett, R. W. B. and Lee, H. B.},
  year = {1967},
  url = {https://ntrs.nasa.gov/citations/19670050438},
  note = {Source identifier: 19670050438}
}