Saya mau tau Lihat pula dari Semigelanggang

François Baccelli, Guy Cohen, Geert Jan Olsder, Jean-Pierre Quadrat, Synchronization and Linearity (online version) , Wiley, 1992,

Golan, Jonathan S., Semirings and their applications. Updated and expanded version of The theory of semirings, with applications to mathematics and theoretical computer science (Longman Sci. Tech., Harlow, 1992, . Kluwer Academic Publishers, Dordrecht, 1999. xii+381 pp.