Declension table of ?puramāṇa

Masculine	Singular	Dual	Plural
Nominative	puramāṇaḥ	puramāṇau	puramāṇāḥ
Vocative	puramāṇa	puramāṇau	puramāṇāḥ
Accusative	puramāṇam	puramāṇau	puramāṇān
Instrumental	puramāṇena	puramāṇābhyām	puramāṇaiḥ puramāṇebhiḥ
Dative	puramāṇāya	puramāṇābhyām	puramāṇebhyaḥ
Ablative	puramāṇāt	puramāṇābhyām	puramāṇebhyaḥ
Genitive	puramāṇasya	puramāṇayoḥ	puramāṇānām
Locative	puramāṇe	puramāṇayoḥ	puramāṇeṣu

Compound puramāṇa -

Adverb -puramāṇam -puramāṇāt