Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Æthelstan:

"

No battles are recorded during the campaign, and chronicles do not record its outcome. By September, however, he was back in the south of England at Buckingham, where Constantine witnessed a charter as subregulus, that is a king acknowledging Æthelstan's overlordship. In 935 a charter was attested by Constantine, Owain of Strathclyde, Hywel Dda, Idwal Foel, and Morgan ap Owain. At Christmas of the same year Owain of Strathclyde was once more at Æthelstan's court along with the Welsh kings, but Constantine was not. His return to England less than two years later would be in very different circumstances.[3]