Sources

1) Source: The Henry Project . External Link
https://fasg.org/projects/henryproject/data/willi000.htm. Reference: Guillaume "Longue Épée" of Normandy [William "Longsword"] (Questionable reliability of evidence)
2) Source: Gesta Normannorum "Two years before his death. as frequently was my habit I was with the exceptional duke RICHARD. son of MARQUIS WILLIAM...yea indeed the rights which [Richard's son Richard] asserted in the realm of his great-grandfather ROLLO... son the still surviving patrician RICHARD. Reference: 1 (Data from secondary evidence)
3) Source: The Ecclesiastical History of England and Normandy: Volume III "After Rollo, a succession of valiant dukes commanded the warlike Normans ; namely, William Longsword, Richard the elder, Richard II., son of Gunnor, and his two sons, Richard the younger and Eobert of Jerusalem, and then "William the Bastard" (Data from secondary evidence)
4) Source: Gesta Normannorum "Thus did William, most sacred duke and most glorious martyr of Christ, complete the course of his combat in the nine hundred and forty third year after the incarnation of the Lord, sixteen days before the kalends of January". Reference: 27 (Data from secondary evidence)
5) Source: The Henry Project . External Link
https://fasg.org/projects/henryproject/data/sprot000.htm. Reference: "Sprota" (Questionable reliability of evidence)
6) Source: The Henry Project . External Link
https://fasg.org/projects/henryproject/data/richa000.htm. Reference: Richard I "Sans Peur" ("the Fearless") (Questionable reliability of evidence)
7) Source: The Ecclesiastical History of England and Normandy: Volume III "For Richard, son of Gonnor, and duke of Normandy, was father of Robert I., whose son was William the Conqueror, the father of Duke Robert, who was father of William the Clito. On the other side, Robert the archbishop and count, who was brother of Duke Richard, had a son named Richard, count of Evreux, which Richard had a daughter called Agnes, wife of Simon, who bore Bertrade, Fulk's mother, and whose daughter Sibylla was." (Data from secondary evidence)
8) Source: Ademari Chronicon "Obiit quoque Richardus Rotomagensis, sepulturae traditus apud Fescannum, et pro eo successit Richardus, filius ejus.". Reference: 996 (Data from direct source)
9) Source: Gesta Normannorum "Having heard about this count herbert. and hugh duke and prince of the whole realm. and also count William of poitou; came hastily to him there... I have come. both so that you might give your sister to me as a wife... on the advice of counts hugh the great. and herbert and of his own fideles; he gave his sister to duke William of poitou... Moreover herbert seeing that William of rouen was strong and was gaining strength. and gleamed affluently in christ through both spiritual and bodily virtue and through very great deeds; on the advice of duke hugh the great. gave his own daughter to that man.". Reference: 22
10) Source: Reg.lat.1283.pt.A Various trees showing the Counts of Anjou and Flanders, including the top-right tree:1. Ingelgerus.1.1 Fulco Rusus.1.1.1 Widdo; 1.1.2 Ingelgerus; 1.1.3 Fulco Bonus.1.1.3.1 Widdo 1.1.3.2 Drogo 1.1.3.3 Gotfridus 1.1.3.4 Blanco.1.1.3.3.1 Maurice 1.1.3.3.2 Fulco 1.1.3.4.1 Constanca regina uxor Rober regis.1.1.3.3.2.1 Gottfridus 1.1.3.3.2.2 Ermengarde 1.1.3.4.1.1 Henricus Rex.1.1.3.3.2.2.1 Gaufridus 1.1.3.3.2.2.2 Fulco 1.1.3.3.2.2.3 Hildegarde.. External Link
https://digi.vatlib.it/view/MSS_Reg.lat.1283.pt.A/0140. Reference: Folio 65v - Genealogia Comitis Andev (Data from direct source)