We consider a random-matrix theory with an external source and discuss the universality of the nearest-neighbour level-spacing probability p(s), which becomes independent of the external source eigenvalues. When the external source eigenvalues are separately given in a wide region, the breakdown of the universality appears. The average of p(s) for the randomly chosen external eigenvalues shows the cross-over from the universal Gaussian unitary ensemble behaviour to Poissonian behaviour. [References: 17]
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