Where can I find the original back/cover/case for it?

Hello, I have a HP SLATE 8 pro tablet, but I've used once a "protective" case for it and it broke the back of the tablet, I'm talking the white part that is mounted on the back of the tablet, here is the pic http://techinews24.com/wp-content/upload...

Where can I find it? And what is the exact name? Thank you