@misc{indiciae1ba123eaf583,
  title = {Estimating Insolation Incident on Tilted Surfaces},
  author = {Elkin, R. E. and Toelle, R. G.},
  year = {1983},
  url = {https://ntrs.nasa.gov/citations/19820000273},
  note = {Source identifier: 19820000273}
}