Õ: "indeks" selles tähenduses pole soovitatav

olemus,
märksõnade asukohtadele viitav loend,
enamasti = register (1a)

Wiktionary:
1. an alphabetical listing of items and their location
The index of a book lists words or expressions and the pages of the book upon which they are to be found.

ülevaateid
https://en.wikipedia.org/wiki/Subject_indexing

vt ka
https://en.wikipedia.org/wiki/Bibliographic_index

https://en.wikipedia.org/wiki/Citation_index