400. That’s an error.

Google cannot redirect you to http://worldcat.org/search?q=Petite+bibliotheque+des+théatres:+Chef-d'œuvres+Philippe+Poisson+jean+baudrais+nicolas-thomas+le+prince 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.