This primary source comes from the Records of the Army Air Forces, ca. 1902 - 1964.
Full Citation: Airscape of Lawrenceville, NJ; 10/5/1939; New Jersey - Lawrenceville; "Airscapes" of American and Foreign Areas, 1917 - 1964; Records of the Army Air Forces, ca. 1902 - 1964, Record Group 18; National Archives at College Park, College Park, MD. [Online Version, https://docsteach.org/documents/document/airscape-of-lawrenceville-nj, May 2, 2024]