Discussiones Mathematicae - General Algebra and Applications
Discussiones Mathematicae - General Algebra and Applications > 2006 > 26 > 2 > 199-217
Discussiones Mathematicae - General Algebra and Applications > 2009 > 29 > 2 > 153-167
Discussiones Mathematicae - General Algebra and Applications > 2006 > 26 > 2 > 199-217
Discussiones Mathematicae - General Algebra and Applications > 2009 > 29 > 2 > 153-167