@article{05296681, title = {Quadratic level quasigroup equations with four variables. I.}, journal = {Publications de l'Institut Math\'ematique. Nouvelle S\'erie}, volume = {82(96)}, year = {2007}, pages = {53-67}, doi = {10.2298/PIM0795053K}, zbl = {1229.39035}, language = {en}, url = {http://dml.mathdoc.fr/item/05296681} }
Krapež, Aleksandar. Quadratic level quasigroup equations with four variables. I.. Publications de l'Institut Mathématique. Nouvelle Série, Tome 82(96) (2007) pp. 53-67. doi : 10.2298/PIM0795053K. http://gdmltest.u-ga.fr/item/05296681/