The references in the German article are apparently more impressive than in the English, but perhaps this is an illusion. German mathematical historians of the 1920's and 1930's were often themselves skillful mathematicians. They discussed Greek mathematics exhaustively, but the amount of material they wrote far exceeds the original material, and should be counted largely as interesting speculation.

Summary of Wikipedia on Eudoxus:

• Insufficient reference to best available sources, in particular no suggestion as to what the ultimate sources are, and how reliable they are.
• Unlike some other well known Greek mathematicians, Eudoxus would probably be remembered for his construction of epicycles even if he hadn't made major contributions to mathematics. Still, his mathematical contributions were, as far as we can tell, profound. But here we have totally inadequate mathematical explanation.