@article{AM2_1971__6_136215,
     author = {WILFRIED IMRICH and G\"UNTER GASZT},
     title = {On the {Lexicographic} and {Costrong} {Product} of {Set} {Systems.} {(\"Uber} das lexikographische und das kostrake {Produkt} von {Mengensystemen)} {(Short} {Communication)}},
     journal = {Aequationes mathematicae},
     pages = {319--320},
     publisher = {mathdoc},
     volume = {6},
     year = {1971},
     zbl = {0229.05141},
     url = {http://geodesic.mathdoc.fr/item/AM2_1971__6_136215/}
}