The International Tables for Crystallography from IUCr is now available online. The full set of all the volumes from Volume A to G including A1 is available.

Volume A Space-group symmetry

Volume A1 Symmetry relations between space groups

Volume B Reciprocal space

Volume C Mathematical, physical and chemical tables

Volume D Physical properties of crystals

Volume E Subperiodic groups

Volume F Crystallography of biological macromolecules

Volume G Definition and exchange of crystallographic data

A guided tour is available, which contains five sample chapters and numerous examples showing the functionality of the site.