Is this one of the last book designs George Salter worked on? The book was published by Alfred Knopf in 1966. George Salter was a book cover designer and graphic artist. He passed away in 1967. The dust jacket below is a cream colored paper.
The book is titled Markings, written by Dag Hammersjold (1905-1961) Swedish diplomat and economist as well as the second Secretary-General of the United Nations, the only person with a Nobel Peace Prize awarded posthumously. Hammerskjold died in a plane crash accident over the then Belgian Congo in Africa in 1961. Accident or conspiracy? (more can be found on a wikipedia search)
The title page below has a photograph of Dag Hammerskold on the opposite side.