1. Beun, J. A., Steenland, M. J., De Klerk, D. and Gorter, C. J., Commun. Kamerlingh Onnes Lab., Leiden No. 300a
2. Further researches on the magnetic properties of potassium chromium alum below 1 °K
3. Beun, J. A., Steenland, M. J., De Klerk, D. and Gorter, C. J., Commun. No. 301a
4. Magnetic researches on adiabatically demagnetized chromium methylamine alum
5. Beun, J. A., Miedema, A. R. and Steenland, M. J., Commun. No. 305d