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2. L.G. Fel, Phys. Rev. E 52, 702 (1995).
3. Throughout the present manuscript we focus on the non-chiral tetrahedratic phase, T d , which has reflection planes and not the chiral tetrahedratic phase, T, [2] which does not. Because of the existence of reflection planes in T d , clockwise and counterclockwise rotations of the 3-fold axis are in the same class. T d has eight 3-fold axes (not four), i.e. 8C3, because left- and right-handed rotations are indistinguishable. In T, clockwise and counterclockwise rotations are in separate classes (4C3 and 4C'3 meaning a hand can be defined for T. See, for example, M. Tinkham, Group Theory and Quantum Mechanics (McGraw Hill Book Company, New York, 1964) pp. 57-58, 328-329.
4. L. Radzihovsky, T.C. Lubensky, Europhys. Lett. 54, 206 (2001).
5. H.R. Brand, H. Pleiner, P.E. Cladis, in preparation.