What is the meaning of I.a.?

Initialism of inter alia.

Initialism of inter aliaj (“among others”).

Abbreviation of inter altri (“among others”)

Abbreviation of inter altere ("among others")

Abbreviation of inter altere (sin. tra l'altro) Latinistic formula and Latin phrase of medioeval italiano, totally obsolete today ("among others")

Source: wiktionary.org

See also