@article{SZHR11,
 author = {Stapleton, Gem and Zhang, Leishi and Howse, John and Rodgers, Peter},
 journal = {IEEE Transactions on Visualization and Computer Graphics},
 month = {jul},
 number = {7},
 pages = {1020-1032},
 title = {Drawing Euler Diagrams with Circles: The Theory of Piercings},
 volume = {17},
 year = {2011}
}