@misc{indiciaec7dfdbfa3cd5,
  title = {Negative Differential Resistance (NDR) frequency conversion with gain},
  author = {Hwu, R. J. and Alm, R. W. and Lee, S. C.},
  year = {1992},
  url = {https://ntrs.nasa.gov/citations/19930018577},
  note = {Source identifier: 19930018577}
}