@misc{indiciaec7bb30ece8e7,
  title = {Solar Electric Propulsion Asteroid Belt Mission Study: Program Development Plan Final Report - Volume 3},
  author = {Springer, F. G.},
  year = {1970},
  url = {https://ntrs.nasa.gov/citations/19700014166},
  note = {Source identifier: 19700014166}
}