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2. J. Lekner, Electrostatics of Two Charged Conducting Spheres, Proceedings of Royal Society A, https://doi.org/10.1098/rspa.2012.0133
3. D.J. Jackson, Classical Electrodynamics, 3rd edn. (John Wiley & Sons, NewYork, 1999)
4. A. Zangwill, Modern Electrodynamics (Cambridge University Press, Cambridge, 2013)
5. J. A. Stratton, Electromagnetic Theory (IEEE PRESS SERIES), https://onlinelibrary.wiley.com/doi/book/10.1002/9781119134640