1. GilbertW.De Magnete Magneticisque Corporibuset de MagnoMagneteTellure (On the Magnet Magnetic Bodies and on the Great Magnet the Earth).London: 1600 (translated 1893 by Mottelay PF Dover Books).
2. History of Permanent Magnet;Moosa I.J;IJRDT,2014
3. HeuslerF StarkW HauptE.Verh. Deutsche Phys. Gessel 5 1903