Demonstratio Mathematica
Demonstratio Mathematica > 1998 > Vol. 31, nr 1 > 25-32
Demonstratio Mathematica > 1998 > Vol. 31, nr 1 > 11-17
Demonstratio Mathematica > 1998 > Vol. 31, nr 1 > 19-23
Demonstratio Mathematica > 1998 > Vol. 31, nr 2 > 345-354
Demonstratio Mathematica > 1998 > Vol. 31, nr 2 > 325-332