Sources

1) Source: The Ecclesiastical History of England and Normandy: Volume III "Eustace, count of Boulogne, who was with William at the battle of Senlac in England, married Ita, daughter of Godfrey, duke of Lorraine, by whom he had Baldwin, Godfrey, and Eustace" (Data from secondary evidence)
2) Source: Genealogia comitum Bulonensium A short genealogy connecting the early Merovingians to the later counts of Boulogne, written circa the 11th century. The earliest generations are almost certainly fictional. Considered a reliable secondary source for generations from Arnulf of Metz onwards. Considered a "primary" source for events from the year 1000 onwards.. External Link
https://www.dmgh.de/mgh_ss_9/index.htm#page/300/ (Data from direct source)
3) Source: Bernold of St. Blasien Chronicle "Duke Godfrey [‘the Bearded’], who was most excellent among secular men, very easily moved to tears by the memory of his sins and most generous in the distribution of alms, rested in peace on Christmas Eve [24 December]". Reference: 1069 (Data from secondary evidence)