Discussiones Mathematicae - General Algebra and Applications
Discussiones Mathematicae - General Algebra and Applications > 2003 > 23 > 2 > 125-137
Discussiones Mathematicae - General Algebra and Applications > 2006 > 26 > 2 > 155-161
Discussiones Mathematicae - General Algebra and Applications > 2003 > 23 > 2 > 125-137
Discussiones Mathematicae - General Algebra and Applications > 2006 > 26 > 2 > 155-161