@misc{indiciaef230a53782b2,
  title = {Earth's magnetic field complex: U.S. National activities during the Decade of Geopotential Field Research},
  author = {Michael E. Purucker and T. Sabaka and W. Kuang and S. Maus and Jeffrey J. Love},
  year = {2009},
  url = {https://pubs.usgs.gov/publication/70200675},
  note = {Source identifier: 70200675}
}