1887 Submarine cable chart of the world, showing also the seacoast stations and the principal connecting land lines; for the use of the navy and mercantile marine, from the Digital Commonwealth - commonwealth 1257b816x. (<a rel="nofollow" class="external free" href="https://www.digitalcommonwealth.org/search/commonwealth:1257b816x">https://www.digitalcommonwealth.org/search/commonwealth:1257b816x</a>)
United States Hydrographic Office
Digital Commonwealth