Which among the Upanishad-s should we treat as authoritative texts? Among the 108 Upanishad-s, are only the 10 Upanishad-s considered as primary Upanishad-s? Those followers of traditions who consider incarnations of Rama or Krishna as the Supreme Being, follow Gopala Tapani Upanishad, Rama Rahasya Upanishad, etc. Can we consider these Upanishad-s?