Nielsen, A. (1968). An investigation on promoted iron catalysts for the synthesis of ammonia (3rd ed.). Gjellerup.
Chicago-referens (17:e uppl.)Nielsen, Anders. An Investigation on Promoted Iron Catalysts for the Synthesis of Ammonia. 3rd ed. Kobenhavn: Gjellerup, 1968.
MLA-referens (8:e uppl.)Nielsen, Anders. An Investigation on Promoted Iron Catalysts for the Synthesis of Ammonia. 3rd ed. Gjellerup, 1968.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.