Do you have information verifying that these images are from the National Archives?
If you have specific captions or citations indicating this, then it is advisable to note that in your book.
Follow the guidelines in this publication: Citing Records in the National Archives of the United States.
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The website you link is run by the Center for Military History, not the National Archives. Much of their artwork is created by artists employed by them and is not included in the holdings of the National Archives.
You should contact the Center for Military History for any questions about the copyright status of anything they publish on their website.