Kibble, Tom W K (1976). "Topology of cosmic domains and strings". Journal of Physics A: Mathematical and General9 (8): 1387–1398. doi:10.1088/0305-4470/9/8/029. Bibcode: 1976JPhA....9.1387K.
Kibble, Tom W K (1976). "Topology of cosmic domains and strings". Journal of Physics A: Mathematical and General9 (8): 1387–1398. doi:10.1088/0305-4470/9/8/029. Bibcode: 1976JPhA....9.1387K.