共 5 条
[1]
CLIFFORD A, 1969, MATH SURVEYS AM MATH, V7
[2]
DRAZIN M, 1979, S REGULAR SEMIGROUPS, P29
[3]
DRAZIN MP, UNPUB NATURAL STRUCT
[4]
SHEHADAH A, 1982, THESIS PURDUE U W LA
[5]
SHEHADAH A, UNPUB COUNTER EXAMPL