400. That’s an error.

Google cannot redirect you to http://cgi.zvab.com/SESSz178166944611148075648/cgi-bin/n_xsearch.cgi?lang=de&tle=Die+Pr%C3%BCfung+der+Treue,+oder:+die+Irrungen.+Ein+Lustspiel+drey+Aufz because the request was invalid.

This might be because the link was created a long time ago. Try your search again on Google. That’s all we know.