Missing Photographs: Ernest Thompson Seton

I am currently doing research on a turn-of-the-twentieth-century photographer named Zaida Ben-Yusuf who created at least two portraits of Ernest Thompson Seton in the fall of 1899. I have attached to this e-mail halftone reproductions of the two images that appeared in popular periodicals at this time. I am trying to track down vintage prints of these two platinum photographs. If anyone knows about the whereabouts of these prints, please call or write me. Many thanks for your assistance with this query.

Sincerely,
Frank H. Goodyear
Assistant Curator of Photographs
National Portrait Gallery
Smithsonian Institution
P.O. Box 37012
Victor Building, Suite 8300 -- MRC 973
Washington, DC 20013-7012
Phone: 202 275-1855