SEARCH Articles Figures Tables Fold axis of symmetry Fold rotation-reflection axis of symmetry Four-fold inversion axis Four-fold rotation axis N-fold improper rotation axis N-fold rotational axis One-fold inversion axis One-fold rotation axis Rotation about an -fold axis of symmetry Rotation infinite fold rotational axis Six-fold inversion axis Six-fold rotation axis Three-fold inversion axis Three-fold rotation axis Two-fold inversion axis Two-fold rotation axis Two-fold rotational symmetry axis