@ARTICLE{topputo2007analytical,
  author = {Topputo, F. and Owis, A. and Bernelli-Zazzera, F.},
  title = {{Analytical Solution of the Feedback Optimal Control in Low-Thrust Transfers}},
  journal = {Aerotecnica, Missili e Spazio},
  year = {2007},
  volume = {86},
  pages = {185--194}
}