authors, Erich Best ... [et al.] ; editors, Hartmut Bergmann ... [et al.] ; chief editor, Ernst Koch ; : gw, : us. -- Springer, 1987. -- (Gmelin handbook of inorganic chemistry / prepared and issued by Gmelin-Institut für Anorganische Chemie der Max-Planck-Gesellschaft zur Förderung der Wissenschaften ; director, Ekkehard Fluck ; System no. 54 . W, tungsten ; suppl. v. A7).