Semigroups
edited by T.E. Hall, P.R. Jones, G.B. Preston
Academic Press, 1980
Buku Teks
Lallement, Gerard, author
Semigroups and combinatorial applications
John Wiley & Sons, 1979
Buku Teks
Algebraic theory of semigroups
edited by G. Pollak
North-Holland Publishing, 1979
Buku Teks