1. Bergerhoff, G. & Brown, I. D. In Crystallographic Databases, edited by F. H. Allen et al. (International Union of Crystallography, Chester, 1987).
2. Materials Project (materialsproject.org).
3. AFLOW (aflowlib.org).
4. OQMD (oqmd.org).
5. NOMAD (www.nomad-coe.eu).