@article{ duan06dmtp,
    author = "Zhenhai Duan and Yingfei Dong and Kartik Gopalan",
    title = "DMTP: Controlling Spam Through Message Delivery Differentiation",
    journal = "Proc. of IFIP Networking, Coimbra, Portugal and In Lecture Notes in Computer Science, Volume 3976, Springer",
    volume = "",
    pages = "",
    year = "May 2006"
}