As mentioned before, I really love Claire’s series on how to live with books. As it happens, I am about to build a new reading-room for myself. I will need ca. 20 m of shelving (roof-to-floor). And I have just discovered a perfect system:

This is string®, designed by the Swedes Kajsa & Nisse Strinning in 1949. The simplicity and flexibility of the system is fantastic. Just what I need!