Hyung Shin Kim Yunju Baek Heung-Kyu Lee Young-Ho Suh Robust Image Watermark Using Radon Transform and Bispectrum Invariants. 145-159 2002 conf/ih/2002 Information Hiding http://link.springer.de/link/service/series/0558/bibs/2578/25780145.htm db/conf/ih/ih2002.html#KimBLS02