@misc{indiciae591e66d34be1,
  title = {Nanoscale Subsurface Imaging via Resonant Difference-Frequency Atomic Force Ultrasonic Microscopy},
  author = {Cantrell, Sean A. and Cantrell, John H. and Lilehei, Peter T.},
  year = {2007},
  url = {https://ntrs.nasa.gov/citations/20080007508},
  note = {Source identifier: 20080007508}
}