- Islandora Repository
- Mss.B.B61_W
- Warburg, Felix M.: From Boas. 1913 Dec. 11
- Warburg, Felix M.: From Boas. 1913 Dec. 17
- Warburg, Felix M.: From Boas. 1913 Dec. 26
- Warburg, Felix M.: From Boas. 1913 Dec. 8
- Warburg, Felix M.: From Boas. 1913 Nov. 11
- Warburg, Felix M.: From Boas. 1914 Apr. 25
- Warburg, Felix M.: From Boas. 1914 Apr. 3
- Warburg, Felix M.: From Boas. 1914 Jan. 5
- Warburg, Felix M.: From Boas. 1919 Jan. 28
- Warburg, Felix M.: From Boas. 1924 Dec. 19
- Warburg, Felix M.: From Boas. 1924 Nov. 15
- Warburg, Felix M.: From Boas. 1924 Oct. 20
