dʒˈeɪ.ˈɛl. ɡɹˈoʊs ænd tˈiː.dˈʌbəljˌuː. tˈʌkɚ nˈaɪntiːnhˈʌndɹɪd sˈɛvənti sˈɛvən,  dʒˈɛnɚɹˌeɪɾɪŋ ˈɔːl ɡɹˈæf kˈʌvɚɹɪŋz baɪ pˌɜːmjuːtˈeɪʃən vˈoʊltɪdʒ ɐsˈaɪnmənts.
J.L. Gross and T.W. Tucker (1977),  Generating all graph coverings by permutation voltage assignments.