Periodic tables

Ram Seshadri's periodic table of the elements listing effective ionic (Shannon-Prewitt) radii

Neutron scattering cross sections from the National Institute of Standards and Technology

NMR periodic table from Bruker

Electronegativity

Crystallography

International Tables, Volume A

Fullprof

GSAS

DiffPy

Density Functional Theory Codes

VASP

Quantum Espresso

ELK

LMTO