Map of Ancient Lake Atna and surrounding area.
United States Department of the Interior, Bureau of Land Management
<a rel="nofollow" class="external free" href="https://www.blm.gov/ak/st/en/fo/gdo/cultural_history/lake_ahtna_research.print.html">http://www.blm.gov/ak/st/en/fo/gdo/cultural_history/lake_ahtna_research.print.html</a>