Coyet, P. J., Bonde, C., & Roberts, M. (1988). Swedish diplomats at Cromwell's court, 1655-1656: The missions of Peter Julius Coyet and Christer Bonde. London: Offices of the Royal Historical Society, University College London.

Coyet, Peter Julius, Christer Bonde, and Michael Roberts. Swedish Diplomats At Cromwell's Court, 1655-1656: The Missions of Peter Julius Coyet and Christer Bonde. London: Offices of the Royal Historical Society, University College London, 1988.

Coyet, Peter Julius, Christer Bonde, and Michael Roberts. Swedish Diplomats At Cromwell's Court, 1655-1656: The Missions of Peter Julius Coyet and Christer Bonde. London: Offices of the Royal Historical Society, University College London, 1988.