400. That’s an error.

Google cannot redirect you to http://worldcat.org/search?q=Las+comedias+d.+Pedro+Calderon+Barca,+corregidas+y+dadas+á+luz+par+J.J.+Keil+senior+pedro+calderón+barca 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.