Podkletnov, Evgeny (September 16, 1997). "Weak gravitation shielding properties of composite bulk Y Ba2Cu3O7−x superconductor below 70 K under e.m. field". arXiv:cond-mat/9701074. This is believed to be substantially the same paper accepted for publication in 1996 by Journal of Physics D which was later withdrawn by the author.