As usual, I have consulted too many texts in the research for this novel to list, but some of the principal books I have relied on are included here:
Bowman, A. K., Garnsey, P. & Cameron, A., (2005) The Cambridge Ancient History: Volume XII, the Crisis of Empire AD 193–337, 2nd edition, Cambridge University Press, Cambridge
Carroll, M., (2001) Romans, Celts and Germans, the German Provinces of Rome, Tempus, Stroud
Goldsworthy, A., (2011) The Complete Roman Army, Thames & Hudson, London
Grant, M., (1996) The Severans, the Changed Roman Empire, Routledge, Abingdon
La Baume, P., (Not known) The Romans on the Rhine, Stollfuss Verlag, Bonn
Mattingly, H., (1948) Tacitus on Britain and Germany, a New Translation of the Agricola and the Germania, Penguin, West Drayton
Matyszak, P., (2020) Forgotten Peoples of the Ancient World, Thames & Hudson, London
Murdoch, A., (2006) Rome’s Greatest Defeat, Massacre in the Teutoburg Forest, The History Press, Stroud
Southern, P., (2001) The Roman Empire from Severus to Constantine, Routledge, Abingdon
Swain, S., Harrison, S. & Elsner, J., (2007) Severan Culture, Cambridge University Press, Cambridge
Syvänne, I., (2017) Caracalla, A Military Biography, Pen & Sword Military, Barnsley