Jean-Marc Deshouillers, François Hennecart, Bernard Landreau. Do Sums of 4 Biquadrates Have a Positive Density?. In Joe Buhler, editor, Algorithmic Number Theory, Third International Symposium, ANTS-III, Portland, Oregon, USA, June 21-25, 1998, Proceedings. Volume 1423 of Lecture Notes in Computer Science, pages 196-203, Springer, 1998. [doi]
Abstract is missing.