Image:Ernst Udet.jpg

Ernst Udet on a Willi Sanke postcard (#653). The Postkartenvertrieb W. Sanke in Berlin published a series of about 600-700 numbered postcards, showing World War I aviators from about 1910 to ca. 1918/20, when he went out of business.[1][2] On some of these postcards, the photographers are identified, such as Fritz Fischer, Nicola Perscheid (1864 - 1930) [3], or Alfred Krauth. On this particular postcard, no photographer was identified.

Immediate image source: [4], linked at [5].

Users Lupo, Rlandmann on en.wikipedia

As these postcards were published before 1923, they are in the public domain in the U.S. In all likelihood, they are even, but without knowing the photographer, we cannot be sure. {{PD-old-70}}

	This image is in the public domain in the United States. In most cases, this means that it was published in the United States prior to January 1, 1923 or that its first publication anywhere in the world was prior to January 1, 1909 or that its copyright expired in the United States.
	This image might not be in the public domain outside of the United States (this especially applies in Canada, China except Macao, Germany or Switzerland). The creator and year of publication are essential information and must be provided. See Wikipedia:Public domain and Wikipedia:Copyrights for more details.

Originally from en.wikipedia; description page is (was) here