Sources

1) Source: Gesta Regum Anglorum "Henricus, junior filius Willelmi magni, natus est in Anglia anno tertio postquam pater eam adierat" (Data from direct source)
2) Source: The Henry Project . External Link
https://fasg.org/projects/henryproject/data/willi001.htm. Reference: William "the Conqueror" (Guillaume "le Conquérant") (Questionable reliability of evidence)
3) Source: The Ecclesiastical History of England and Normandy: Volume III "At the same time, Stephen, count de Blois, son of Theobald, count de Chartres, who was son-in-law of "William, king of England, took the cross and departed for Jerusalem" (Data from secondary evidence)
4) 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)
5) 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)
6) Source: Genealogia comitum Flandrensium ex libro Florido et Chronico Aldenburgensi, etc "Balduinus vero insulanus duxit Athelam filiam Roberti, regis Francorum de qua genuit Balduinum montensem et Robertum et Mathilden reginam anglorum, uxorem Willelmi noti."
7) Source: The Henry Project . External Link
https://fasg.org/projects/henryproject/data/matil000.htm. Reference: Matilda of Flanders (Questionable reliability of evidence)
8) Source: Chronica Magistri Rogeri de Houdene "He [Henry I] was succeeded by Stephen, his nephew, who reigned nineteen years" (Data from secondary evidence)
9) Source: The Ecclesiastical History of England and Normandy: Volume III “The Countess Adela contributed large sums for the pope's expenses… William, the eldest, married the daughter of Gilo de Sulli… and left a worthy offspring, Odo, Rahier… Theobald, count Palatine… married Matilda, daughter of Duke Ingelbert… As for Stephen, the third son of Stephen de Blois, having been knighted by his uncle Henry, and taken prisoner William count of Mortain at the battle of Tinchebrai, the king granted him that county. He married Matilda, daughter of Eustace count of Boulogne, by his wife Mary ; and in her right inherited all his states” (Data from secondary evidence)
10) Source: The Henry Project . External Link
https://fasg.org/projects/henryproject/data/henry001.htm. Reference: Henry I (Questionable reliability of evidence)
11) Source: Chippenham & Stanleigh Deeds "Maud the Empress, daughter of King Henry [I] and Henry her son, Duke of Normandy"Dated: Probably 1151 Evidence for Matilda being Henry's daughter. External Link
http://discovery.nationalarchives.gov.uk/details/r/9071ca5f-ff22-495e-b2f7-9135696a0eec. Reference: 1213/1 (Data from direct source)
12) Source: Chronica Magistri Rogeri de Houdene "after whose death [Stephen] Henry, the son of Geoffrey, earl of Anjou, and of Matilda, the former empress of the Romans, and daughter of the before-named king Henry the First, took the helm of the kingdom of England" (Data from direct source)
13) Source: The Ecclesiastical History of England and Normandy: Volume III "when Prince Henry ascended the throne of England, he married Matilda, by whom he had William the Etheling, and Matilda the empress" (Data from secondary evidence)
14) Source: The Ecclesiastical History of England and Normandy: Volume III "This king, four months after he succeeded to the throne, disdaining to abandon himself to illicit connections, and be like horse and mule which have no understanding, married with royal pomp Matilda, a noble lady, by whom he had two children, Matilda and William." (Data from secondary evidence)
15) Source: The Ecclesiastical History of England and Normandy: Volume III "At the same time he married another daughter to Rotro count of Mortain, who bore her husband a daughter named Philippa." (Data from secondary evidence)
16) Source: English Baronies: a Study of Their Origin and Descent, 1086-1327. Reference: Page 6; Barony of Gloucester (Questionable reliability of evidence)
17) Source: Orderici Vitalis Historiæ Ecclesiasticæ Within a year of her coronation, Matilda bore a son called Henry: "Anno ab incarnatione Domini MLXVIII... priusquam annus perficeretur, filium nomine Henricum peperit.". Reference: Book 4 (Data from secondary evidence)