@misc{indiciae2a84edffd510,
  title = {On the length-difficulty relation in skill performance.},
  author = {Noble, M. and Swink, J. and Trumbo, D.},
  year = {1967},
  url = {https://ntrs.nasa.gov/citations/19670066247},
  note = {Source identifier: 19670066247}
}