@misc{indiciae6aae679dba6f,
  title = {Problems of extremely long-duration missions in the inner solar system - Example Helios},
  author = {Kehr, J. and Porsche, H. and Heftman, K.},
  year = {1979},
  url = {https://ntrs.nasa.gov/citations/19790069296},
  note = {Source identifier: 19790069296}
}