The Yiddish Book Center in Amherst, Massachusetts, a non-profit
organization, has hundreds of thousands of Yiddish Books.
http://www.yiddishbookcenter.org/ I don't believe hard copies are for
sale, however, many are digitized and the one's you are looking for
may be among them. More are being digitized all the time.

Joseph Hirschfield
Portage, MI USA
HIRSCHFELD, HERSZFELD, BUXBAUM, BUCHSBAUM, LINDENBAUM-Skwarzawa,
Gliniany, Sielec Bienkow, Jaryczow Nowy -- Galicia
MINOWICKI, MINOWITZKI, MINOFF-Brest Litovsk, Wysoko Litovsk -- Belarus

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My grandfather I.M.Wajsenberg (Weissenberg,Vaysenberg,)
was an yiddish writer ,died in 1939.
I am trying to buy,get his books. It is not an easy thing.
I wrote to Universities , libraries here, bookshops.
He was not (nearly not) printed after the war.
I leave in Israel, will pay shipping, etc
Please, any real help.

Wajsenberg Mark
mark306@bezeqint.net