Army List and Directory, 20 April 1937: the entry for Herbert S. Clarkson at the Field Artillery School, Fort Sill.
Image · dated 20 April 1937 · source: U.S. War Department publication (Internet Archive scan); armylistdirector1937unit.

How it is shown: Complete page as supplied; no crop, no retouch, no search highlight.
Keep in mind: Confirmed as printed. A federal government publication, released public although dated after 1931.