This is wrong. The date was not April 18, 1976 but actually April 10, 1976.

Here the list of the dates in Germany.

7 April 1976 – Munich, Olympiahalle
8 April 1976 – Düsseldorf, Philipshalle
10 April 1976 – West Berlin, Deutschlandhalle
11 April 1976 – Hamburg, Congress Center Hamburg
12 April 1976 – Hamburg, Congress Center Hamburg
13 April 1976 – Frankfurt, Festhalle Frankfurt
14 April 1976 – Ludwigshafen, Friedrich-Ebert-Halle