A familiar name in an ancient title can create a false shortcut. You recognise “Thomas” and assume that the reference points to the work you already know. Before reading further, establish which text the author means.
Use the catalogue identifiers
NASSCAL’s Book of Thomas entry identifies it as ECCA 615 and locates its Coptic manuscript in Nag Hammadi Codex II, pages 138–145. It lists the Gospel of Thomas as related literature, rather than treating the titles as interchangeable.
That distinction gives you a clean starting point without requiring an immediate theory about the relationship between the works.
Make an identity card for your reading
Write the title used by your edition, its editor or translator, the catalogue identifier and the manuscript reference. If another article uses a different title, check its identifiers before merging your notes.
A shared personal name does not, by itself, establish common authorship, identical contents or a single historical community. Each claim needs its own argument.
Follow one reference at a time
Use the bibliography to locate an edition or translation, then record the exact publication you consulted. A bibliography entry is a route to a book, not proof that you have read it.
For the physical distinction behind the reference, see why a codex and a work are different things.