Reference:

Gayle Leen, Jaakko Peltonen, and Samuel Kaski. Focused multi-task learning in a Gaussian process framework. Machine Learning, 89(1-2):157–182, 2012.

Suggested BibTeX entry:

@article{Leen12,
    author = {Gayle Leen and Jaakko Peltonen and Samuel Kaski},
    journal = {Machine Learning},
    language = {eng},
    number = {1-2},
    pages = {157-182},
    title = {Focused multi-task learning in a {G}aussian process framework},
    volume = {89},
    year = {2012},
}