Mss.B.B61_W

Warburg, Felix M.: From Boas. 1933 Oct. 9

Warburg, Felix M.: From Boas. 1935 July 15

Warburg, Felix M.: From Boas. 1935 Oct. 23

Warburg, Felix M.: From Boas. 1936 Aug. 20

Warburg, Felix M.: From Boas. 1937 Feb. 26

Warburg, Felix M.: From Boas. 1937 Mar. 22

Warburg, Felix M.: To Boas. 1906 May 8

Warburg, Felix M.: To Boas. 1908 June 1

Warburg, Felix M.: To Boas. 1912 Nov. 21

Warburg, Felix M.: To Boas. 1913 Dec. 18

Warburg, Felix M.: To Boas. 1913 Dec. 24

Warburg, Felix M.: To Boas. 1913 Dec. 5