@misc{indiciaeca71354b6202,
  title = {A note concerning observable but not controllable modes, and stability.},
  author = {Desoer, C. A. and Forys, L. J.},
  year = {1969},
  url = {https://ntrs.nasa.gov/citations/19690062146},
  note = {Source identifier: 19690062146}
}