1. Compare: Jean Becquerel, Commun. Kamerlingh Onnes Lab., Leiden 211a; Jean Becquerel and W. J. de Haas, Commun. Kamerlingh Onnes Lab. Leiden 211b and 211c.
2. On the Paramagnetic Rotation of Tysonite
3. Handelingen 26e Nederl. Nat. en Geneesk. Congres;van den Handel,1937