Field of study: Astronomy, Geodesy, Physics, Sterrenkunde

• A photographical method of research into the structure of the galaxy
  KNAW, Proceedings, 14 II, 1911-1912, Amsterdam, 1912, pp. 579-584
  
  
• Calculation of Dates in the Babylonian Tables of Planets
  KNAW, Proceedings, 19 I, 1917, Amsterdam, 1917, pp. 684-703
  
  
• Expansion of a cosmic gassphere, the new stras and the Cepheids
  KNAW, Proceedings, 21 I, 1919, Amsterdam, 1919, pp. 730-742
  
  
• Further Remarks on the Dark Nebulae in Taurus (reprint from Proceedings 23 (1921), 720-726)
  Gems from a century of science 1898-1997. Centenary issue of the Proceedings of the Royal Netherlands Academy of Arts and Sciences, Schoonhoven, L.M. (eds), Amsterdam, 1997, pp. 294-300
  
  
• Investigation of a galactic cloud in Aquila
  KNAW, Proceedings, 21 II, 1919, Amsterdam, 1919, pp. 1323-1337
  
  
• Researches into the structure of the galaxy
  KNAW, Proceedings, 13 I, 1910, Amsterdam, 1910, pp. 239-258
  
  
• Some remarks on the reversibility of molcular motions
  KNAW, Proceedings, 6, 1903-1904, Amsterdam, 1904, pp. 42-48
  
  
• The Distance of the Dark Nebulae in Taurus (reprint from Proceedings 23 (1921), 707-719)
  Gems from a century of science 1898-1997. Centenary issue of the Proceedings of the Royal Netherlands Academy of Arts and Sciences, Schoonhoven, L.M. (eds), Amsterdam, 1997, pp. 281-293
  
  
• The luminosity of stars of different types of spectrum
  KNAW, Proceedings, 9 I, 1906, Amsterdam, 1906, pp. 134-148
  
  
• The Origin of the Saros
  KNAW, Proceedings, 20 II, 1918, Amsterdam, 1918, pp. 943-955
  
  
• The relation between the spectra and the colours of the stars
  KNAW, Proceedings, 9 I, 1906, Amsterdam, 1906, pp. 292-302
  
  
• The variability of the Pole-star
  KNAW, Proceedings, 15 II, 1912-1913, Amsterdam, 1913, pp. 1192-1199