@article{SF_1982__24_134545,
     author = {M. Yamada},
     title = {P-systems in regular semigroups.},
     journal = {Semigroup forum},
     pages = {173--188},
     publisher = {mathdoc},
     volume = {24},
     year = {1982},
     zbl = {0479.20030},
     url = {http://geodesic.mathdoc.fr/item/SF_1982__24_134545/}
}