@article{AM2_1989__37_2-3_137309,
     author = {R. Craigen and Z. P\'ales},
     title = {The associativity equation revisited.},
     journal = {Aequationes mathematicae},
     pages = {306--312},
     publisher = {mathdoc},
     volume = {37},
     number = {2-3},
     year = {1989},
     zbl = {0676.39005},
     url = {http://geodesic.mathdoc.fr/item/AM2_1989__37_2-3_137309/}
}