1. R. Mueller-Ernesti, German Patent 910-602, 1941.
2. Duplication of magnetic tape recording by contact printing;Herr;Tele-Tech,1949
3. Duplicating magnetic tape by contact printing;Camras;Electron,1949
4. Magnetic tape duplication by contact printing at short wavelengths;Sugaya;IEEE Trans. Magn.,1969
5. Chromium dioxide particles for magnetic recording;Auweter;IEEE Trans. Magn.,1990