Former Formula One Champion Michael Schumancher has been admitted to hospital in Switzerland, his spokesman said.
Earlier, his family said he had left hospital in France and was going to continue his "long phase of rehabilitation".
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The annual event has earned a place in the record books ahead of the grand final of the 60th anniversary show in Austria this evening.
Local authorities said the move is necessary to "avert the growing number of deaths and increasing harm linked to psychoactive substances".
Some students argued that the centuries-old tradition of wearing gowns, suits and mortarboards to exams was 'archaic' and looked elitist.