While vols. III/29 A, B (published in 1992 and 1993, respectively) contains the low frequency properties of dielectric crystals, in vol. III/30 the high frequency or optical properties are compiled. While the first subvolume 30 A contains piezooptic and elastooptic constants, linear and quadratic electrooptic constants and their temperature coefficients, and relevant refractive indices, the present subvolume 30 B covers second and third order nonlinear optical susceptibilities. For the reader's convenience an alphabetical formula index and an alphabetical index of chemical, mineralogical and technical names for all substances of volumes 29 A, B and 30 A, B are included.