@book{
  international1991iaea,
  title={International Centre for Theoretical Physics, Trieste: Scientific Activities in 1990},
  series={TECDOC Series},
  number={625},
  year={1991},
  url={https://www.iaea.org/publications/881/international-centre-for-theoretical-physics-trieste-scientific-activities-in-1990},
  publisher={INTERNATIONAL ATOMIC ENERGY AGENCY},
  address={Vienna}
}