Bernhard Riedl Veronika Grascher Mathias Kolb Thomas Neubauer Economic and Security Aspects of Applying a Threshold Scheme in e-Health. 39-46 2008 ARES http://doi.ieeecomputersociety.org/10.1109/ARES.2008.175 conf/IEEEares/2008 db/conf/IEEEares/ares2008.html#RiedlGKN08