- CollectionCamb. Medieval History - Papers relating to the Cambridge Medieval History Series
- SeriesBox 1-2 - Letters to and from contributing historians to Cambridge Medieval History
- SubseriesBox 1 - Letters relating to historians A-L
- File24 - Letters from C. Diehl
- Item1 - Copy of letter, in French, 'Cher Monsieur', from C. H. Diehl
- Item2 - Autograph letter, signed, to Monsieur Whitney from C. H. Diehl, Paris