If I can find no evidence that a writer or artist left an estate, and their work was published over 100 years ago, is it safe to assume it is public domain and therefor, free to use?
Specifically I'm trying to find out if a poem by Wilfred Owen, an Englishman who died 1918 in France, is available to use in a book intended for public sale in America. The poem was published in 1918. So far I can't find any evidence that his family or an estate holds the copyright to his works. His wikipedia article mentioned:
In 1975 Mrs. Harold Owen, Wilfred's sister-in-law, donated all of the manuscripts, photographs and letters which her late husband had owned to the University of Oxford's English Faculty Library.
If the poem was a part of those manuscripts, does it now belong to Oxford even though it was already published?