1. L. G. P. Saavedra, in: Quantum Information and Quantum Control Conference (Fields Institute and University of Toronto, Toronto, Canada, 19–23 July, 2004) [ http://www.fields.utoronto.ca/programs/scientific/04-05/quantumIC/posters/index.html ].
2. L. G. P. Saavedra, in: The 9th International Conference on Squeezed States and Uncertainty Relations (Besan¸con, France, 2–6 May, 2005), Int. J. Mod. Phys. B, 20, 1428 (2006).
3. L. G. P. Saavedra, in: The 38th Symposium on Mathematical Physics “Quantum Entanglement and Geometry” (Toruñ, Poland, 4–7 June, 2006), Int. J. Open Sys. Inform. Dyn., 14, 319 (2007).
4. E. Corinaldesi, Nuovo Cimento, Suppl. 10, serie 9, 2, 83 (1953).
5. N. Bohr and L. Rosenfeld, Mat.-Fys. Medd. Dan. Vid. Selsk., 12, 65 (1933) [English translation, in: J. A. Wheeler and W. H. Zurek (eds.), Quantum Theory and Measurement, Princeton University Press, MS, USA (1983), p. 479].