Dissertations from the Instituut-Lorentz: 1971-1980 1971: S. Emid On the relativistic dynamics of systems of dipoles and quadrupoles 1971: C.M. Fortuin On the random-cluster model 1972: Th.J. Siskens On the theory of diamagnetic relaxation in harmonic oscillator assemblies 1973: C.A.W. Citteur Critical behaviour of Ising systems on extremely anisotropic lattices 1973: J. de Goede On some aspects of the electrodynamic behaviour of material systems 1974: C.P. Louwerse Dispersion relation calculations for pion electroproduction and Compton scattering 1974: K.J.F. Gaemers Hard photon corrections for processes in e+e- colliding beam experiments 1975: P.A.J. Tindemans Systems with separable interactions 1976: L.M. Hafkenscheid On the dielectric properties of molecular crystals 1976: E.J. van Dongen On the theory of one-dimensional spin 1/2 systems 1976: S.N.M. Ruijsenaars Quantum theory of relativistic charged particles in external fields 1976: H.J.M. Boots On the theory of multiple scattering 1978: R.J. Boel On certain relations between spin correlation functions of Ising models 1979: J.H.H. Perk Time-dependent correlations in the one-dimensional XY-model 1979: L.W.J. den Ouden Separable many-particle interactions and stability of critical behaviour 1980: G. van der Zwan On some aspects of fluctuating hydrodynamics 1980: J.W. van Holten On the construction of supergravity theories