One or more of the preceding sentencesincorporates text from a publication now in the public domain:Chisholm, Hugh, ed. (1911). "Wire". Encyclopædia Britannica. Vol.28 (11thed.). Cambridge University Press. pp.738–739.
Swiger Coil Systems. "Edgewound Coils". Swiger Coil Systems, A Wabtec Company. Archived from the original on 19 December 2010. Retrieved 1 January 2011.
Swiger Coil Systems. "Edgewound Coils". Swiger Coil Systems, A Wabtec Company. Archived from the original on 19 December 2010. Retrieved 1 January 2011.