Ante-Nicene Fathers Volume 5
Caius the Presbyter: Fragments
As the Introductory Notice points out, Caius is a mostly unknown figure with many works attributed to him (most notably the "Muratorian Canon"), but none certainly his.
The fragments themselves are worth skimming, especially since the whole section is short and on having finished it you can claim to have read all or most of what we have from this shadowy apologist.
In these fragments, we see a concern for the supremacy of Scripture over tradition and claims to apostolic teaching handed down privately or personally. We see also the concern for orthodox Christology and a unified church around Christ.
So read and enjoy, it's short!