@misc{indiciaec98cc2e24fa2,
  title = {Angles of multivariable root loci},
  author = {Thompson, P. M. and Stein, G. and Laub, A. J.},
  year = {1982},
  url = {https://ntrs.nasa.gov/citations/19830038102},
  note = {Source identifier: 19830038102}
}