# Data Sources

Physical constants
  NIST Physics Laboratory - Constants, units and uncertainty
Atomic and isotope mass
  NIST Physics Laboratory - Atomic weights and isotope composition
Atomic density
  ILL Neutron Data Booklet
Covalent Radii
  Cordero, et al., Dalton Trans., 2008, 2832-2838, doi:10.1039/801115j
Magnetic form factors
  Brown. P. J., In International Tables for Crystallography, Volume C, Wilson. A. J. C (ed), section 4.4.5
Neutron scattering factors
  Atomic Institute for Austrian Universities
X-ray scattering factors
  Center for X-Ray Optics
Neutron activation
  `IAEA (1987) Handbook on Nuclear Activation Data. TR 273 (International Atomic Energy Agency, Vienna, Austria, 1987).

<http://cds.cern.ch/record/111089/files/IAEA-TR-273.pdf>`_

> Shleien, B., Slaback, L.A., Birky, B.K., (1998). Handbook of health physics and radiological health. Williams & Wilkins, Baltimore.

Crystal structure
  Ashcroft and Mermin
Oxidation states

  wikipedia: List of oxidation states of the elements

  Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements, 2nd ed. Butterworth-Heinemann. pp. 27–28. ISBN 0-08-037941-9.

FASTA and biomolecule formulas
  Perkins (1988), Modern Physical Methods in Biochemistry Part B, 143-265.