Subject headings for books are established by the Book Industry Study Group (BISG). Your book’s entry in the master digital book catalog will have three (3) subject headings. Subject headings commonly have a top level and a sub-level heading. We welcome your input into selecting the most appropriate subject headings for your book. Below is a partial list of most common top level headings, with a list of sub-headings that will appear when you click on these: