13th Observation Squadron emblem
<a href="https://en.wikipedia.org/wiki/United_States_Army_Institute_of_Heraldry" class="extiw" title="en:United States Army Institute of Heraldry">en:United States Army Institute of Heraldry</a>
2017-09-02
Hubbard, Gerard (June 1943). "Aircraft Insignia, Spirit of Youth". Vol. LXXXIII (No. 6) National Geographic, pp. 710-722 modified with Microsoft Paint