Citation: Wyckoff, R. W. G. (1935). Page 55 from the second edition supplement of The Structure of Crystals by Wyckoff R W G. Published by Reinhold Publishing Corporation, INC,Camden, N. J. in 1935 http://jcrystal.com/steffenweber/gallery/StructureTypes/st4.html . The second edition supplement of The Structure of Crystals, , pp. 55-55.