400. That’s an error.

Google cannot redirect you to http://worldcat.org/search?q=Cartas+y+relaciones+Hernan+Cortés+al+emperador+Carlos+V.+colegidas+e+ilustradas+por+Pascual+Gayangos+hernán+cortés 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.