1. Anonymous, 1993. Rice, Wheat and Barley. Monthly statistics of agriculture forestry and fisheries, statistics and information department. Ministry of Agriculture Forestry and Fisheries, Tokyo, pp. 14–15. (In Japanese)
2. Anonymous, 1994. Crop Hectarage by Prefecture in 1992. Monthly statistics of agriculture forestry and fisheries, statistics and information department. Ministry of Agriculture Forestry and Fisheries, Tokyo, pp. 104–105. (In Japanese)
3. Anonymous, 1996a. The report on the 27th annual census of waterfowls (Anatidae) in January, 1996. Wildlife Protection Division, Nature Conservation Bureau, Environment Agency Japan, Tokyo, pp. 345. (In Japanese with English summaries)
4. Anonymous, 1996b. Rice, Wheat and Barley. Monthly statistics of agriculture forestry and fisheries, statistics and information department. Ministry of Agriculture Forestry and Fisheries, Tokyo, pp. 12–13. (In Japanese)
5. Anonymous, 1997. Vegetables. Monthly statistics of agriculture forestry and fisheries, statistics and information department. Ministry of Agriculture Forestry and Fisheries, Tokyo, pp. 18–27 (In Japanese)