Sources

1) Source: Kingscote Family Papers "Maurice de Berchal' [Berkeley] son of Robert, son of Harding, to Adam son of Nigel, son of Arthur, Maurice's nephew.". External Link
http://discovery.nationalarchives.gov.uk/details/r/ae91310b-9ccf-45b4-a1c8-0fbd66e3accf. Reference: D471/T1/4 (Data from direct source)
2) Source: The Berkeley Estate "King Henry II and Maurice son of Robert FitzHarding.Grant by Henry, as king, of the same, to hold by service of five knights."Date: 1154. External Link
http://discovery.nationalarchives.gov.uk/details/r/1e709784-6490-48d4-9af8-ccea7bbf1abd. Reference: BCM/A/1/1/5 (Data from direct source)
3) Source: The Berkeley Estate "Robert FitzHarding and Roger de Berckele. Agreement made in Robert's house at Bristol, in the presence of Henry duke of Normandy, for Robert's son Maurice to marry Roger's daughter, with Slimbridge, being £10 worth, for her portion, and for Roger's son Roger to marry Robert's daughter, "Dated: after 1153. Reference: BCM/A/1/43/62 (Data from direct source)
4) Source: English Baronies: a Study of Their Origin and Descent, 1086-1327. Reference: Pages 13-14: Berkeley (Questionable reliability of evidence)
5) Source: Duchy of Lancaster: Royal Charters "Grant to Miles de Gloucester of Sybil daughter of Bernard de Neufmarché in marriage"Dated: 1121. External Link
http://discovery.nationalarchives.gov.uk/details/r/C3540439. Reference: DL 10/6
6) Source: The Berkeley Estate "Alice widow of Maurice de Berkeley and Thomas de Berkeley her son."Dated: 1190-1215. External Link
http://discovery.nationalarchives.gov.uk/details/r/ba25e873-4977-4843-a865-230e31e7eba3. Reference: BCM/A/2/17/6 (Data from secondary evidence)