400. That’s an error.

Google cannot redirect you to http://worldcat.org/search?q=Relazioni+d'alcuni+viaggi+fatti+diverse+parti+della+Toscana+per+osservare+le+produzioni+naturali,+e+gli+antichi+monumenti+di+essa+giovanni+targioni-tozzetti 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.