authors, Manfred Irmler ... [et al.] ; editors, Hartmut Bergmann ... [et al.] ; C12a : gw - C12b : us. -- Springer, 1994-. -- (Gmelin handbook of inorganic and organometallic chemistry / prepared and issued by Gmelin-Institut für Anorganische Chemie der Max-Planck-Gesellschaft zur Förderung der Wissenschaften ; director, Ekkehard Fluck ; system no. 39 . Rare earth elements ; C12).