Akrigg, 1968, p. 30; Cokayne, 1953, p. 128. Akrigg, G.P.V. (1968). Shakespeare and the Earl of Southampton. Cambridge, Massachusetts: Harvard University Press.Cokayne, G.E. (1953). The Complete Peerage edited by Geoffrey H. White. XII (Part I). London: St. Catherine Press.
According to Akrigg, Southampton and Derby were "rather close friends at this period"; Akrigg, 1968, p. 56. Akrigg, G.P.V. (1968). Shakespeare and the Earl of Southampton. Cambridge, Massachusetts: Harvard University Press.