@misc{indiciae88fc8b233e5e,
  title = {Soil penetrometer},
  author = {Howard, E. A. and Hotz, G. M. and Bryson, R. P.},
  year = {1968},
  url = {https://ntrs.nasa.gov/citations/19730023589},
  note = {Source identifier: 19730023589}
}