1. 千葉県教育委員会（Education board of Chiba Prefecture）, 1988, 地学資料．上総層群上部鍵層集（Geological Datum Key Tephra Beds of the Upper Kazusa Group）（1987年版）. 145p． English translation from the original written in Japanese.
2. 千葉県教育委員会（Education board of Chiba Prefecture）, 1989, 地学資料, 上総層群下部・安房層群（仮）鍵層集（Geological Datum Key Tephra Beds of the Lower Kazusa Group and Awa Group）（1988年版）. 370p. English translation from the original written in Japanese.
3. 千葉県立中央博物館（Natural History Museum and Institute, Chiba）, 1991, 地学資料, 上総層群下部鍵層集（Geological Datum Key Tephra Beds of the Lower Kazusa Group）（1990年版）. 218p. English translation from the original written in Japanese.
4. 藤岡導明・亀尾浩司（Fujioka, M. and Kameo, K.）, 2004, テフラ鍵層に基づく銚子地域の犬吠層群小浜層と房総半島の上総層群黄和田層, 大田代層および梅ヶ瀬層との対比（Correlation between the Obama Formation of the Inubou Group in the Choshi district and the Kiwada, Otadai and Umegase Formations of the Kazusa Group in the Boso Peninsula, central Japan, based on key tephra layers）. 地質雑（Jour. Geol. Soc. Japan）, 110, 480–496.
5. 藤岡導明・亀尾浩司・小竹信宏（Fujioka, M., Kameo, K. and Kotake, N.）, 2003, テフラ鍵層に基づく横浜地域の大船層・小柴層と房総半島の黄和田層との対比（Correlation based on key tephra layers between the Ofuna-Koshiba Formations in the Yokohama district and Kiwada Formation in the Boso Peninsula, central Japan）. 地質雑（Jour. Geol. Soc. Japan）, 109, 166–178.