@misc{indiciae03cbc4131c2e,
  title = {Color differentiation by computer image processing},
  author = {Billingsley, F. C. and Goetz, A. F. H. and Lindsley, J. N.},
  year = {1970},
  url = {https://ntrs.nasa.gov/citations/19700056981},
  note = {Source identifier: 19700056981}
}