- Niko, S., 1998a:
- Kobayashiceras gifuense, a new actinocerid cephalopod from the Lower Devonian of Japan.
- Journal of Paleontology, vol. 72, no. 1, pp. 36–38.
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- Niko, S., 1998b:
- First discosorid cephalopod from Japan.
- Paleontological Research, vol. 2, no. 2, pp. 145–147.
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- Niko, S., 1998c:
- Devonian tentaculitids from central and northeast Japan.
- Paleontological Research, vol. 2, no. 4, pp. 279–282.
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- Niko, S., 2000a:
- Youngest record of tentaculitoids: Hidagaienites new genus from near the Carboniferous-Permian boundary in central Japan.
- Journal of Paleontology, vol. 74, no. 3, pp. 381–385.
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- Niko, S., 2000b:
- New cephalopod material from the Bashkirian (Middle Carboniferous) of the Ichinotani formation, central Japan.
- Paleontological Research, vol. 4, no. 4, pp. 255–260.
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- Niko, S., 2001:
- Middle Carboniferous orthoconic cephalopods from the Omi limestone group, central Japan.
- Paleontological Research, vol. 5, no. 2, pp. 115–120.
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- Niko, S., 2002a:
- Revision of an Ordovician cephalopod Ormoceras yokoyamai (Kobayashi, 1927).
- Paleontological Research, vol. 6, no. 1, pp. 121–124.
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- Niko, S., 2002b:
- Echigoceras sasakii, a new Middle Carboniferous nautilid from the Omi limestone group, central Japan.
- Paleontological Research, vol. 6, no. 4, pp. 351–355.
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- Niko, S., 2005:
- Redescription of the Ordovician cephalopod genus Centroonoceras Kobayashi, 1934.
- Journal of Paleontology, vol. 79, no. 5, pp. 1028–1030.
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- Niko, S., 2007:
- Stratigraphy of the Devonian Fukuji formation in Gifu Prefecture and its favositid coral fauna.
- Bulletin of the National Museum of Nature and Science. Series C, vol. 33, pp. 57–79.
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- Niko, S. and Ehiro, M., 2002:
- Permian orthoconic cephalopods of the Ochiai formation in the southern Kitakami mountains, northeast Japan.
- Paleontological Research, vol. 6, no. 4, pp. 385–389.
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- Niko, S. and Hamada, T., 1986:
- The Middle Silurian foraminifer (Saccamminopsis) from the Gion-yama formation, central Kyushu.
- Scientific Papers of the College of Arts and Sciences, the University of Tokyo, vol. 36, no. 2, pp. 173–178.
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- Niko, S. and Hamada, T., 1987:
- Adnatoceras from Middle Carboniferous of the Ichinotani formation, Fukuji district, central Japan.
- Transactions and Proceedings of the Palaeontological Society of Japan. New Series, no. 148, pp. 223–227.
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- Niko, S. and Hamada, T., 1988:
- Early Devonian receptaculitid (Ischadites) from the Fukuji formation, central Japan.
- Journal of the Geological Society of Japan, vol. 94, no. 5, pp. 337–342, pl. 1.
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- Niko, S., Hamada, T. and Yasui, T., 1989:
- Silurian Orthocerataceae (Mollusca: Cephalopoda) from the Yokokurayama formation, Kurosegawa terrane.
- Transactions and Proceedings of the Palaeontological Society of Japan. New Series, no. 154, pp. 59–67.
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- Niko, S., Kakuwa, Y., Watanabe, D. and Matsumoto, R., 1999:
- Early Silurian actinocerid and orthocerid cephalopods from the Kerman area, east-central Iran.
- Paleontological Research, vol. 3, no. 1, pp. 41–48.
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- Niko, S. and Nishida, T., 1987:
- Early Permian cephalopods from the Mizuyagadani formation, Fukuji district, central Japan.
- Transactions and Proceedings of the Palaeontological Society of Japan. New Series, no. 146, pp. 35–41.
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- Niko, S. and Nishida, T., 2000:
- A new pseudorthoceratid cephalopod from the Kazanian (middle Late Permian) of Japan.
- Paleontological Research, vol. 4, no. 1, pp. 53–55.
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- Niko, S. and Nishida, T., 2003b:
- Devonohelicoceras hidaense, a new torticonic oncocerid (Cephalopoda) from the Lower Devonian of central Japan.
- Proceedings of the Japan Academy, Series B, vol. 79, no. 7, pp. 201–206.
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