Linked from
The 14 pages that link to Avesta, each with the reason it gives.
AshaRelated: The Avesta preserves Asha's religious and liturgical contexts.
AvestanRelated: It is the principal body of literature in which Avestan is preserved.
FrashokeretiRelated: Avestan passages provide early foundations for ideas of final renewal.
ZoroasterRelated: Its oldest hymns, the Gathas, are traditionally attributed to Zoroaster.
MithraRelated: Its hymns and liturgies preserve key evidence about Mithra.