Althorp Papers. Vols. mcccxcii, mcccxciii. Letters to Frederick Spencer from his son John Poyntz Spencer (afterwards 5th Earl Spencer); 1845-1857, n.d. Content includes discussion of school affairs, family health and news and his travels in America between July and November 1857. Two volumes.
Althorp Papers. Vol. mcccxciv. Letters to Frederick Spencer from other family members; 1844 -1857. Content includes discussion of family health and news and mutual acquaintances. For the correspondence of Adelaide, Countess Spencer, see Northamptonshire Record Office, SOX130, circa 1860 and SOX2...
Althorp Papers. Vols. mcccxcvii-mcccxcix. Drafts and retained copies of correspondence by Frederick Spencer; 1811-1857. Including memoranda, notebooks, and legal documents such as passport, details of marriage settlement and codicil. A register of letters, circa 1825, can be found at Northamptonshire Record Office, SOX293. Three volumes.