1. For reviews see:
2. Photochromism: Molecules and Systems (Eds.: H. Dürr, H. Bouas-Laurent), Elsevier, New York, 1990;
3. Molecular Devices and Machines: A journey into the Nano World (Eds.: V. Balzani, A. Credi, M. Venturi), Wiley-VCH, Weinheim, 2003;
4. The Art of Building Small: From Molecular Switches to Molecular Motors