Wed May  9 12:43:46 CEST 2007
Corrected the indices in 1(e) of Hausaufgaben. Thanks to Felix Janda for noticing the misprint.
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Fri May 11 10:44:28 CEST 2007
Corrected the apostrophe of the e-tensor in 1(c) of Hausaufgaben. Thanks to Matthias Leiß for noticing the misprint.