From Online Dictionary of Crystallography
Groupes de Sohncke (Fr), Gruppi di Sohncke (It).
Sohncke groups are called the 65 three-dimensional space groups containing only operations of the first kind (rotations, rototranslations, translations). It is very generally accepted that enantiomerically-pure compounds (e.g. proteins) crystallise in these groups. The term comes from Leonhard Sohncke (Halle, 22 February 1842 – München, 1 November 1897), German mathematician.