The extension to the non-centrosymmetric space groups was made some years later.    From Wordnik.com.  [Herbert A. Hauptman - Autobiography] Reference

In this monograph we introduced also the concepts of the structure invariants and seminvariants, special linear combinations of the phases, and used them to devise recipes for origin specification in all the centrosymmetric space groups.    From Wordnik.com.  [Herbert A. Hauptman - Autobiography] Reference