[Koha] Extracting authorities from Biblios

[Toni]

Hello,
We are currently using Koha 3.0.5 but we have not been using authorities
and we would like to start using them.
Is there a way to extract authorities from existing Biblios?
Doing some searches on the Internet I saw some posts talking about an
script "migration_tools/auth_from_biblio.pl" that doesn't seem to exist
anymore in Koha 3. Was it deprecated? Is there a new way of extracting
auths (populating them) from biblios?

Regards,
Toni