1. R. Dedekind, Göttingen Abhandlungen 23, 1–23 (1878).
2. J. Montes and E. Nort, J. Algebra 146, 318–334 (1992).
3. M. Kumar and S. K. Khanduja, Commun. Algebra (in press).
4. Yu. L. Ershov, Multiply Valued Fields (Nauchaya Kniga, Novosibirsk, 2000) [in Russian].
5. S. K. Khanduja, Preprint (Panjab Univ., Chandigarh, 2006).