Delgado-Friedrichs, OlafHyde, StephenO'Keeffe, MichaelYaghi, Omar M2020-12-202020-12-201040-0400http://hdl.handle.net/1885/217944We call attention to methods of enumerating periodic structures and to the databases that contain them. These provide information essential to the systematic design of crystalline materials. The underlying topology is uniquely specified and identifiable from the Systre key which is thus the topological genomeapplication/pdfen-AU201710.1007/s11224-016-0853-32020-11-23