@article{ARM_1973_9_3_a4,
     author = {Chajda, Ivan},
     title = {On substitution of operations in systems of equations over algebras},
     journal = {Archivum mathematicum},
     pages = {135--139},
     year = {1973},
     volume = {9},
     number = {3},
     mrnumber = {0345894},
     zbl = {0279.08005},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ARM_1973_9_3_a4/}
}