Calliphon and Democedes of Croton are not attested as a writing pair. Democedes of Croton is a late 6th-century BCE ἱατρός. Herodotus places him at the courts of Polycrates of Samos and Darius I. Calliphon is named as his father, a worshipper of Asclepius, not as a writer of medical books.
No medical autograph survives under either name. What this site holds is a short collection of Testimonies.
The pairing on this page is a later heading. There is no joint book and no school founded by the two.
Available Works
Testimonies
Μαρτυρίαι
6 passages
Also published as PDF.