That the above images (from Eakins’ studio) of a nude elderly man are authentic images of the “good grey bard”, poet Walt Whitman, was first argued by Ed Folsom in the Spring 1994 issue of the Walt Whitman Quarterly Review.
Since then, there have been some fairly convincing refutations (see William Innes Homer – “Whitman, Eakins and the Naked Truth” in the Summer 1997 edition of the same journal), but, well, look again – we do know he (Walt) was a friend of Eakins (even sat for him for his portrait on one singularly memorable occasion), and that is an extraordinary resemblance – the jury is still out.
Another Whitman “find” – again remarked upon by Ed Folsom in the pages of the Walt Whitman Quarterly Review , is the (re-)discovery, a few years back, of a rare (wax cylinder) tape-recording from circa 1889-90, purportedly of Whitman reading (four lines from his late poem, “America”).
Again, there are the nay-sayers and the firm believers. Folsom discusses the case here.
Allen Koenigsberg has some additional information in Antique Phonograph Monthly. Vol.X No 3 – [2018 update this link is no longer available]
oh and Allen was always proud of “The Gay Succession”, explained in full detail here