@article{MZ_1955__62_169489,
     author = {Alfred L. Foster},
     title = {The identities of - and unique subdirect factorization within - classes of universal algebras.},
     journal = {Mathematische Zeitschrift},
     pages = {171--188},
     publisher = {mathdoc},
     volume = {62},
     year = {1955},
     zbl = {0064.26301},
     url = {http://geodesic.mathdoc.fr/item/MZ_1955__62_169489/}
}