@inProceedings{PolicellaEtAl2009b,
    author =    {Policella, Nicola and Oliveira, Henrique and Donati,
                 Alessandro and Siili, Tero},
    title =     {{SOHO}'s Keyhole Periods Problem: Definition and a  
Solving Model},
    booktitle = {Proceedings of the CEAS 2009 European Air and Space
                 Conference},
    crossref =  {CEAS2009},
    note =      {Accepted},
}
@proceedings{CEAS2009,
    title =   {Proceedings of the CEAS 2009 European Air and Space
               Conference},
    city =    {Manchester, UK},
    month =   oct,
    year =    2009,
}