1. Letter Gentlemen Seventeen, 8–10–1685, KITLV, H 45.
2. Innes Robert LeRoy , ‘The Door Ajar: Japan's Foreign Trade in the Seventeenth Century’, unpublished dissertation, University of Michigan 1980, p. 319.
3. Letter Gentlemen Seventeen, d.d. 1–11–1678, KITLV, H 45.
4. Notes additionelles sur Tcheng Houo et ses voyages;T'oung Pao,1933