San Francisco collector Harry "Hunk" Anderson's 1973 letter to Leo Castelli is now in the Archives of American Art. I am going to take a wild guess and say that his awesome letterhead was designed by his good friend Ellsworth Kelly. Which would be awesome. I wonder if Moo got some, too.
UPDATE: Awesome, but incorrect. While Kelly's Spectrum paintings may have been one of the references or inspirations, a quick email to the folks at the Anderson Collection finds that Palo Alto graphic designer Sam Smidt created the awesome letterheads for Hunk--and Moo, too.
And now we know.
Harry Anderson letter to Leo Castelli, 1973 Mar. 30 [aaa.si.edu via letterheady]
About the Anderson Collection [aacollection]
Previously: What I Looked At Today: Ellsworth Kelly's Writing]