β
½¬21N4
β
½¬21N5
β
½¬21N6
β
½¬21N7
β
½¬21N8
β
½¬21N9
β
½¬21N10
β
½¬21N11
β
½¬21N12
β
½¬22N1
β
½¬22N2
β
½¬22N3