Lihat Juga

• Earth-currents and a proposed method for their investigation
  oleh: Burbank, J. E.
  Terbitan: (1905)
• A study of pressure and temperature effects in earth-current measurements
  oleh: Mauchly, S. J.
  Terbitan: (1918)
• Earth-Current Observations
  oleh: Bauer, L. A.
  Terbitan: (1922)
• On the interpretation of earth current observations
  oleh: Schuster, Arthur
  Terbitan: (1898)
• XII. On the existence of vertical earth-air electric currents in the United Kingdom
  oleh: Rücker, A. W.
  Terbitan: (1896)