@techreport{weko_32675_1,
   author	 = "MartinJ.DÜrst and TosiyasuL.Kunii",
   title	 = "Error - Free Image Compression with Gray Scale Quadtrees and its Optimization",
   year 	 = "1989",
   institution	 = "Department of Information Science  Faculty of Science The University of Tokyo, Department of Information Science  Faculty of Science The University of Tokyo",
   number	 = "98(1989-AL-012)",
   month	 = "nov"
}