1901 Panama route, map showing location of proposed canal, by the Isthmian Canal Commission (U.S.), from the Digital Commonwealth - commonwealth 4m90fk109. (<a rel="nofollow" class="external free" href="https://www.digitalcommonwealth.org/search/commonwealth:4m90fk109">https://www.digitalcommonwealth.org/search/commonwealth:4m90fk109</a>)
Isthmian Canal Commission (U.S.)
Digital Commonwealth