Reference:

Eerika Savia, Kai Puolamäki, and Samuel Kaski. Latent grouping models for user preference prediction. Machine Learning, 74(1):75–109, 2009.

Suggested BibTeX entry:

@article{Savia09ml,
    author = {Eerika Savia and Kai Puolam\"aki and Samuel Kaski},
    journal = {Machine Learning},
    number = {1},
    pages = {75--109},
    title = {Latent grouping models for user preference prediction},
    volume = {74},
    year = {2009},
}