Essentials of crystallography
Edward Henry Kraus
This text is intended for beginners and aims to present the essential features of geometrical crystallography from a standpoint which combines the ideas of symmetry with those of holohedrism, hemihedrism，etc. All forms possible in the thirty-two classes of symmetry are discussed even though representatives of several of the classes have not as yet been observed among minerals or artificial salts.In each system，however, the important classes are indicated so that the book may readily be used for abridged courses.
