Space Weather Quarterly citation:

Frissell, N. A., E. S. Miller, S. R. Kaeppler, F. Ceglia, D. Pascoe, N. Sinanis, P. Smith, R. Williams, and A. Shovkoplyas (2014), Ionospheric Sounding Using Real-Time Amateur Radio Reporting Networks, Space Weather, 12, 651–656, doi:10.1002/2014SW001132 link)

Eos citation:

Zastrow, M. (2015), Radio blackout! Ham radio as an operational and scientific instrument, Eos, 96, doi:10.1029/2015EO024075. Published on 16 February 2015.