Anne Stafford (daughter of Humphrey) as 2nd wife of Sir John Clinton, 6th Baron Clinton (c.1429 - 29 Feb 1488) is at https://en.wikipedia.org/wiki/John_Clinton,_6th_Baron_Clinton citing http://www.thepeerage.com/p22803.htm#i228028 who references
BP2003 volume 1, page 824. See link for full details for this source. Hereinafter cited as. [S37]
[S37] BP2003. [S37]
[S6] G.E. Cokayne; with Vicary Gibbs, H.A. Doubleday, Geoffrey H. White, Duncan Warrand and Lord Howard de Walden, editors, The Complete Peerage of England, Scotland, Ireland, Great Britain and the United Kingdom, Extant, Extinct or Dormant, new ed., 13 volumes in 14 (1910-1959; reprint in 6 volumes, Gloucester, U.K.: Alan Sutton Publishing, 2000), volume III, page 316. Hereinafter cited as The Complete Peerage