1. Bolton Wv (1906) Angew Chem 19:1537–1540
2. Agte C, Vacek J (1959) Wolfram und Molybdän. Akademie-Verlag, Berlin
3. Rieck GD (1967) Tungsten and its compounds. Pergamon Press, Oxford
4. Zelikman AN, Nikitina LS (1978) Vol’fram (in Russian). Metallurgija, Moskva
5. Pink E, Bartha L (1989) The metallurgy of doped non-sag tungsten. Elsevier, London