En letero al Charles Norton, 30-a de dec. 1906. 'I have given up my professorship and all my official duties and am living as a free lance, spending the better part of my time and energy for the propagation of the idea of the international auxiliary languages.' William James Papers, Houghton Library, Harvard University. Citita laŭ Holt, Niles R., Wilhelm Ostwald's ‘The Bridge’, British Journal for the History of Science, vol. 10, Part 2, no. 35, July 1977, pp. 146-150., piednoto 12.
Wilhelm Ostwald: Wider das Schulelend. Ein Notruf von Dr. Wilhelm Ostwald. Akademische Verlagsgesellschaft m. b. H., Leipzig 1909. (Prelego kontraŭ lerneja mizero) online
