"http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=31891"^^ . . . "http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=121-11-66"^^ . "\"Electromagnetic Wave Phase Speed\" is the ratio of angular velocity and wavenumber." . "c" . "\\(c = w/k\\) where \\(w\\) is angular velocity and \\(k\\) is angular wavenumber."^^ . . "Electromagnetic Wave Phase Speed"@en . .