1. Hypothetical views regarding the connection between the state of the Sun and terrestrial magnetism;Stewart;Encyclopaedia Brilannica,1882
2. Allgemeine Theorie des Erd-magnetismus “Resultate aus den Beobachtungen des magnetischen Vereins im Jahre 1838”;Gauss;publ. C. F. Gauss and W. Weber, Leipzig.,1839
3. The diurnal variation of terrestrial magnetism;Schuster;Phil. Trans. Roy. Soc. (London),1889
4. On the elevation of the electrically conducting strata of the Earth's atmosphere;Kennelly;Elec. World Eng.,1902
5. Telegraphy I. Theory;Heaviside;Encyclopaedia Britannica (10th ed.),1902