Letters found in books from Sassoon's library, mostly from authors sending copies of their work. The correspondents are Hugh Adamthwaite (1942); N.L. Bright (1947); Leonard Clark (1951-3); Sir Ian Critchett (1946); Basil Dowling (1946); Andr Gide (1929); Kenneth Horkins (1949-50); Gerard Irvine (undated); Frank Kendon (1955); H[arold] L[aski] (1928); Agnes Mackay (1948); Stella Morton (1959); Ranald Newson (1930s); Edgar Newgass (1941-55), John Macnair Reid (1928); Bertrand Russell, 3rd Earl Russell (undated); Stanley Snaith (1946); and Raymond Tong (1951).
 Letters to Sassoon from other sources. The correspondents are Margot Asquith, Countess of Oxford and Asquith (1923); Willa Cather (1930); Rosamond Lehmann (1935); Lady Ottoline Morrell (1923-35); Edith Olivier (1929); and Gwen Raverat .
 Further letters found mostly in books. The correspondents are Sir Henry Thirkill, Master of Clare (1953-4); Sir Sidney C. Roberts, Master of Pembroke (1953); Nicholas G.L. Hammond (1955); Monica Brooksbank (1966); Ben W. Hiebsch (1928); Edmund S.P. Haynes (1946); Dorothy Saunders (1954); H. Ulric S. Nisbet (1942); and L. Cherniavsky (1936).