Help please! Do you know these poets?

Over the past year or so I have been gathering poems about the species in the Gaelic Tree Alphabet for an anthology, which will be published in the autumn by Saraband. It will be called Into the Forest - A Celtic Alphabet of Tree Poems. The whole process has been a delight so far, but I'm reaching the part of the process I was warned about by other anthologists: finding copyright holders to seek permission to reprint poems.

About 80% of the poems are either published in books by successful publishers, or I know or have been easily able to make contact with the poets. Without exception I have had lovely messages of support, encouragement and enthusiasm from the poets whose poems I have asked to use.

But now I've reached the last 20%, I have a list of poets who I don't know how to contact. Mostly I found their poems in magazines, now defunct, or in books whose publisher no longer exists. I've asked on Facebook for leads for them all. There are also poets I know to be dead, but don't know who holds their copyright.

So, I am appealing to the world, please, if you know how to contact any of these poets, or know who holds their copyright, please contact me (hag@worldforests.org) and let me know!

A J McGeoch, Andrew Landsdowne, Alice V Stuart, Annette Berman, Barbara Cormack, Colin Oliver, David Nicol, Derek Bowman, Eric MacDonald, Francis Duggan, Harry Rutherford, Ian MacDonald, Jay Howard, Jean Monahan, John Esterbrook, Moira Cattell, Rob King, Robert B Shaw and William Oxley.

And the ones I know to be dead: Gabriela Mistral, George Bruce, Louis McKee, Margaret Winefride Simpson, Tom Rawling and William Heinesen

Any leads much appreciated.  Thank you!