Campbell, Stuart (19 June 2014). "The Missing Questions". Wings Over Scotland. Archived from the original on 13 September 2021. Retrieved 13 September 2021.
Campbell, Stuart (19 June 2014). "The Missing Questions". Wings Over Scotland. Archived from the original on 13 September 2021. Retrieved 13 September 2021.
"Of no materiality". Wings Over Scotland. 27 May 2020. Archived from the original on 4 January 2022. Retrieved 1 August 2022.