1. Adukov, V.M.: Wiener-Hopf equations on a subsemigroup of a discrete Abelian group. I, VINITI AN SSSR, N2431-78, 1978 [Russian].
2. Arens, R. and Singer, I.M.: Generalized analytic functions, Trans Amer. Math. Soc.81 (1956), N 2, 379?393.
3. Coburn, L.A. and Douglas, R.G.: C*-algebra on halfspace. I, Inst. Hautes Etudes Sci. Publ. Math. 1971, N 40, 59?67.
4. Coburn, L.A., Douglas, R.G., Schaeffer, D.C. and Singer, I.M.: C*-algebra on half-space. II. Index Theory, Inst. Hautes Etudes Sci. Publ. Math. 1971, N 40, 69?79.
5. Fuchs, L.: Partially ordered algebraic systems, Pergamon Press, Oxford-London-New-York-Paris, 1963.