Quantum and string shape fluctuations in the dual monopole Nambu–Jona–Lasinio model with dual Dirac strings M. Faber, A.N. Ivanov, A. Müller, N.I. Troitskaya and M. ZachEur. Phys. J. C, 7 4 (1999) 685-695DOI: https://doi.org/epjc/v7/p685(epjc1034)