In Hew Strachan's 'The First World War', in the Global War chapter, he mentions that one title used was the 'Great European War' and that some have described it as a European civil war. I was hoping someone could help me find some source's which actually support this argument.
I doubt you will find much supporting the stance of WW1 being a "civil war". As to have a civil war one must first be a united entity. Europe was and still is not a united body.