@article{ELMA_1994__49_1_141568,
     author = {Vagn Lundsgaard Hansen},
     title = {The {Magic} {World} of {Geometry} - {III.} {The} {Dirac} {String} {Problem.}},
     journal = {Elemente der Mathematik},
     pages = {149--154},
     publisher = {mathdoc},
     volume = {49},
     number = {1},
     year = {1994},
     zbl = {0834.57007},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1994__49_1_141568/}
}