* 延長年号

[1] 
[CITE@ja-JP[刀剣と歴史 (211)]], [[日本刀剣保存会]], [TIME[1928-07]], [TIME[2026-03-18T03:11:57.000Z]], [TIME[2026-04-03T16:32:07.837Z]] <https://dl.ndl.go.jp/pid/7901081/1/28?keyword=%E9%A4%8A%E5%92%8C> (要登録)

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