@article{SF_1974__6_133968,
     author = {M. Yamada},
     title = {Orthodox semigroups whose idempotents satisfy a certain identity.},
     journal = {Semigroup forum},
     pages = {113--128},
     year = {1974},
     volume = {6},
     zbl = {0255.20038},
     url = {http://geodesic.mathdoc.fr/item/SF_1974__6_133968/}
}