The “Black Bridge” on the Verde River Railroad downstream of Perkinsville, Arizona, USA
Alvin L. Medina, USFS per <a rel="nofollow" class="external autonumber" href="http://www.fs.fed.us/rm/pubs/rmrs_gtr291.html">[1]</a>
<a rel="nofollow" class="external text" href="http://www.fs.fed.us/rm/pubs/rmrs_gtr291/rmrs_gtr291_019_072.pdf">Chapter 2: Historical and Pictorial Perspective of the Upper Verde River.</a> In: Synthesis of Upper Verde River research and monitoring 1993-2008. Gen. Tech. Rep. RMRS-GTR-291. USDA Forest Service. 2012. page 64