Dorothea Lange Printing Questions

[TXForester]

Asking this for a friend. Did Dorothea Lange make any of her own prints? If not, were they made by the Farm Security Administration? If a person has a print that is older than the oldest you could have obtained from the Library of Congress, is there a way to determine if it dates back to the FSA days? I'm thinking water marks on the back of the paper or anything that could date the paper from the 1930's.

Thanks