Nave, Carl R. (2010). "Bar Magnet". Hyperphysics. Dept. of Physics and Astronomy, Georgia State Univ. Archived from the original on 2011-04-08. Retrieved 2011-04-10.
Nave, Carl R. (2010). "Bar Magnet". Hyperphysics. Dept. of Physics and Astronomy, Georgia State Univ. Archived from the original on 2011-04-08. Retrieved 2011-04-10.