"Quinquevalent" nitrogen and the structure of ammonium salts: contribution of Alfred Werner and others.
D002621:Chemistry / Q000266:history*; D049672:History, 19th Century; D049673:History, 20th Century; D009584:Nitrogen; D000644:Quaternary Ammonium Compounds; D012492:Salts; D013557:Switzerland
D000644:Quaternary Ammonium Compounds; D012492:Salts; D009584:Nitrogen