For relations with Alexios in Constantinople, John Pryor, ‘The oath of the leaders of the Crusade to the Emperor Alexius Comnenus: Fealty, homage’, Parergon 2 (1984), pp. 111–41 is sensible, as is Ralph-Johannes Lilie, ‘Noch einmal zu dem Thema “Byzanz und die Kreuzfahrerstaaten”’, Poikila Byzantina 4 (1984), pp. 121–74. Absolutely crucial, however, is Jonathan Shepard’s ‘When Greek meets Greek: Alexius Comnenus and Bohemund in 1097–8’, Byzantine and Modern Greek Studies 12 (1988), pp. 185–277.
On Antioch, see Bernard Bachrach, ‘The siege of Antioch: A study in military demography’, War in History 6 (1999), pp. 127–46; John France, ‘The departure of Tatikios from the Crusader army’, Bulletin of the Institute of Historical Research 44 (1971), pp. 137–47; Geoffrey Rice, ‘A note on the battle of Antioch, 28 June 1098: Bohemund as tactical innovator’, Parergon 25 (1979), pp. 3–8. Randall Rogers, Latin Siege Warfare in the 12th Century (Oxford, 1992), is an excellent guide to siege warfare of this period and the efforts against Nicaea and Antioch in particular.
For the kingdom established in the east in 1099 Jerusalem, Joshua Prawer, The Latin Kingdom of Jerusalem: European Colonialism in the Middle Ages (New York, 1972); Jean Richard, The Latin Kingdom of Jerusalem (London, 1979); Alan Murray, The Crusader Kingdom of Jerusalem: A Dynastic History 1099–1125
(Oxford, 2000). For Antioch, see Thomas Asbridge’s excellent The Creation of the Principality of Antioch 1098–1130 (Woodbridge, 2000). Also see the important recent work by Christopher MacEvitt, The Crusades and the Christian World of the East: Rough Tolerance (Philadelphia, 2008). For the patriarch of Jerusalem, see Michael Matzke, Daibert von Pisa: Zwischen Pisa, Papst und erstem Kreuzzug (Sigmaringen, 1998).
For the Italian city-states, see Marie-Louise Favreau-Lilie, Die Italiener im Heiligen Land vom ersten Kreuzzug bis zum Tode Heinrichs von Champagne (1098– 1197) (Amsterdam, 1988); for their relations with Byzantium, Ralph-Johannes Lilie’s Handel und Politik zwischen dem byzantinischen Reich und den italienischen Kommunen Venedig, Pisa und Genua in der Epoche der Komnenen und der Angeloi (1081–1204) (Amsterdam, 1984) is still hard to beat.
For the Bohemond expedition against Byzantium, see John Rowe, ‘Paschal II, Bohemund of Antioch and the Byzantine Empire’, Bulletin of the John Rylands Library 49 (1966), pp. 165–202. Also see Luigi Russo, ‘Il viaggio di Boemundo d’Altavilla in Francia’, Archivio storico italiano 603 (2005), pp. 3–42.
For the creation of the history of the First Crusade, see James Powell, ‘Myth, legend, propaganda, history: The First Crusade, 1140–c.1300’, in Autour de la Première Croisade, pp. 127–41, and also two outstanding articles by Nicholas Paul, ‘Crusade, memory and regional politics in twelfth-century Amboise’, Journal of Medieval History 31 (2005), pp. 127–41, and also ‘A warlord’s wisdom: Literacy and propaganda at the time of the First Crusade’, Speculum 85 (2010), pp. 534–66.