Check Character Systems using Quasigroups: I. - G. B. Belyavskaya; V. I. Izbash; Gary L. Mullen (Des. Codes Cryptogr., 2005)

Check Character Systems Using Quasigroups: II. - G. B. Belyavskaya; V. I. Izbash; Gary L. Mullen (Des. Codes Cryptogr., 2005)