@misc{indiciae9b7cda74168b,
  title = {Normal Incidence for Graded Index Surfaces},
  author = {Khankhoje, Uday K. and Van Zyl, Jakob},
  year = {2011},
  url = {https://ntrs.nasa.gov/citations/20150006618},
  note = {Source identifier: 20150006618}
}