@book{ international1968iaea, title={Theory of Condensed Matter (Trieste, 3 Oct. - 18 Dec. 1967)}, series={Proceedings Series}, year={1968}, isbn={92-0-130068-9}, url={https://www.iaea.org/publications/2178/theory-of-condensed-matter-trieste-3-oct-18-dec-1967}, publisher={INTERNATIONAL ATOMIC ENERGY AGENCY}, address={Vienna} }