@misc{indiciae78aee55cc71a,
  title = {Optical network synthesis using birefringent crystals. VI - Additional techniques for the synthesis of lossless double-pass networks},
  author = {Ammann, E. O. and Yarborough, J. M.},
  year = {1967},
  url = {https://ntrs.nasa.gov/citations/19670011195},
  note = {Source identifier: 19670011195}
}