The reference for the AQUA and PROCHECK-NMR programs is:-

The reference for the original PROCHECK programs is:-

The statistical analyses that underlie the geometrical analyses performed by PROCHECK are described in:-

A statistical analysis of some protein NMR structures, and a description of the concepts of circular variance and notional resolution, are given in:-

The G-factors calculated by PROCHECK-NMR are described in the AQUA/PROCHECK-NMR paper cited above, but also in:

The reference for the Brookhaven Protein Data Bank (PDB) is:

The IUPAC/IUBMB/IUPAB recommendations for the presentation of NMR structures are given in:

The definitions of the Kabsch & Sander secondary structure assignments are given in:-

The reference for Ooi numbers is:-