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Vincent, 2004. Vincent, Nicholas (2004). «Bohun, Humphrey (IV) de, second earl of Hereford and seventh earl of Essex (d. 1275)». Oxford Dictionary of National Biography. Oxford: Oxford University Press. doi:10.1093/ref:odnb/2775.|fechaacceso= requiere |url= (ayuda)
Waugh, 2004. Waugh, Scott L. (2004). «Bohun, Humphrey (VI) de, third earl of Hereford and eighth earl of Essex (c.1249-1298)». Oxford Dictionary of National Biography. Oxford: Oxford University Press. doi:10.1093/ref:odnb/2776.|fechaacceso= requiere |url= (ayuda)