@misc{indiciae9324160576bf,
  title = {Transformational Systems Concepts and Technologies for Our Future in Space},
  author = {Howell, J. T. and George,P. and Mankins, J. C. and Christensen, C. B.},
  year = {2004},
  url = {https://ntrs.nasa.gov/citations/20040110971},
  note = {Source identifier: 20040110971}
}