分数イデアル
↑ Bourbaki 1998, Ch. VII, §1.
↑ Bourbaki 1998, Ch. VII, § 1, n. 7. Proposition 11..
↑ http://projecteuclid.org/DPubS/Repository/1.0/Disseminate?view=body&id=pdffirstpage_1&handle=euclid.rmjm/1187453107