Map of Gatun dam including upper approach wall to locks. A. B. Nichols Notebook Vol. Sup. Vols. 43, 50. Section 1. Unfolded map. 1909-1913.
A. B. Nichols Notebook. Volume 48A. Page 57. Gatun upper locks. West chamber. 1912.
Molded caissons... New docks, Balboa terminals. September, 1911. A.B. Nichols Notebook Vol. 48A. Page 9.