@article{KHD02,
 author = {Keim, Daniel A. and Hao, Ming C. and Dayal, Umeshwar},
 journal = {IEEE Transactions on Visualization and Computer Graphics (TVCG)},
 month = {Jul},
 number = {3},
 pages = {255--269},
 title = {Hierarchical Pixel Bar Charts},
 volume = {8},
 year = {2002}
}