 In 1964, Pyotr Ufimtsev, a Soviet mathematician, published a seminal paper titled "Method of Edge Waves in the Physical Theory of Diffraction" in the journal of the Moscow Institute for Radio Engineering, in which he showed that the strength of the radar return from an object is related to its edge configuration, not its size.Ufimtsev was extending theoretical work published by the German physicist Arnold Sommerfeld.Ufimtsev demonstrated that he could calculate the radar cross-section across a wing's surface and along its edge.