A group of sketches is found in the Theatermuseum (theatre collection) in Vienna, as part of the estate of the singer Anna Bahr-von Mildenburg (1872-1947). They are contained in a sketchbook that Mahler probably used at the very end of his life.
A card by Anna Bahr-von Mildenburg (1872-1947) accompanying the small volume bears the following inscription: "Gustav Mahler's last sketch book. It lay on his breast when he died. His father-in-law (the painter Carl Julius Rudolf Moll (1861-1945)) took it with him and gave it to me today, 25-01-1943, when he visited me. I also gave him letters from Gustav Mahler to read".
Part of the sketches is the Last sketch book Symphony No. 7.