Georges Duby, The Three Orders: Feudal Society Imagined, trans. Arthur Goldhammer (London, 1980), p. 151; Riley-Smith, First Crusade, p. 3
951
Marc Bloch, Feudal Society, trans. L. A. Manyon (London, 1961), pp. 296, 298
952
Georges Duby, The Early Growth of the European Economy: Warriors and Peasants from the Seventh to the Twelfth Century, trans. Howard B. Clarke (Ithaca, NY, 1974), p. 49
