Pressing the button next to a search field opens the respective search index. In the indexes you can search for the official form of an entry. Entries with alternative forms referring to the official form are helpful (for example concerning author names). Author and short title are listed in the same line.
Further you can find in the subject heading index synonym forms, broader terms, narrower terms and related terms. These terms are listed in so-called authority records, but they are also visible as entry lines in the subject heading index.
By clicking a term you can reach the corresponding index entry.