Magnet levitation at your fingertips A. K. Geim, M. D. Simon Nature 400, 323 (1999)
We inadvertently omitted a second reference to the work of I. A. H. Boerdijk (Philips Res. Rep. 11, 45–56; 1956), where the first demonstration, to our knowledge, of levitation of a magnet using non-superconducting diamagnetic materials as stabilizers was reported. The more stable two-sided configuration was first described by Ponisovskii (Prib. Tekh. Eksp. 24, 7–14; 1981). We were unaware of the earlier work until our experiments were completed.
The online version of the original article can be found at 10.1038/22444