@misc{indiciaef7cb86bafb8c,
  title = {Optical image subtraction techniques, 1975-1985},
  author = {Liu, Hua-Kuang and Chao, Tien-Hsin},
  year = {1986},
  url = {https://ntrs.nasa.gov/citations/19870055385},
  note = {Source identifier: 19870055385}
}