an Entity references as follows:
A Bradel binding (also called a bonnet or bristol board binding) is a style of book binding with a hollow back. It most resembles a in that it has a hollow back and visible joint, but unlike a case binding, it is built up on the book. Characteristic of the binding is that the material covering the outside boards is separate from that covering the spine. Many bookbinders consider the Bradel binding to be stronger than the Case binding.