Wengen was working especially on Javanese people in Suriname. These studies are not included.
1957 Social aspects of the co-operative movement in Ceylon and Southern India, Amsterdam: Dico, 137 p. – PhD thesis Leiden University.
1974 & C. van de Loo, Luisteren naar het Boeddhisme, ‘s-Gravenhage: Stichting Nederlandse onderwijs televisie (Ontmoetingen met de wereldgodsdiensten), 25 p.