"BHO is a database in English on the history of the printed book and libraries. It contains titles of books and articles on the history of the printed book worldwide. It is based on ABHB, the Annual Bibliography of the History of the printed Book and Libraries. This annual book publication is a collaboration of editors in more than 30 countries. Since 1989, the Department of Special Collections of the KB has formed the editorial board and maintained a cumulative database. The database contains more than 24.500 records. The files can be searched by names of authors, editors, title words, classification, geographical keywords, names of persons (printers, publishers etc.), firms and institutions, and by titles of periodicals. Subjects covered by BHO correspond with those of ABHB: all scholarly valuable books and articles which relate to the history of the printed book and libraries; also focusing on book production, distribution, conservation, description and analysis; with references to the history of the arts, crafts, techniques, and equipment in relation to books; and including the book and library in their economic, social and cultural environment."