@phdthesis{Zie05,

    author    = "Cai-Nicolas Ziegler",
    title     = "Towards Decentralized Recommender Systems",
    year      = "2005",
    month     = "June",
    school    = "Albert-Ludwigs-Universit{\"a}t Freiburg",
    address   = "Freiburg i.Br., Germany"
}