1ἰσχῦσαι — ἰσχύω to be strong aor inf act …
Greek morphological index (Ελληνική μορφολογικούς δείκτες)
2ἰσχύσαι — ἰσχύ̱σαῑ , ἰσχύω to be strong aor opt act 3rd sg …
3ἴσχυσαι — ἴσχῡσαι , ἰσχύω to be strong aor imperat mid 2nd sg …