Xia Mu Niu Cheng Yong Shao Xiao Tong Wang GIS Watermarking: Hiding Data in 2D Vector Maps. 123-155 2007 Intelligent Multimedia Data Hiding: New Directions http://dx.doi.org/10.1007/978-3-540-71169-8_6 series/sci/2007-58 db/series/sci/sci58.html#NiuSW07