Declension table of ?śirasya

Masculine	Singular	Dual	Plural
Nominative	śirasyaḥ	śirasyau	śirasyāḥ
Vocative	śirasya	śirasyau	śirasyāḥ
Accusative	śirasyam	śirasyau	śirasyān
Instrumental	śirasyena	śirasyābhyām	śirasyaiḥ śirasyebhiḥ
Dative	śirasyāya	śirasyābhyām	śirasyebhyaḥ
Ablative	śirasyāt	śirasyābhyām	śirasyebhyaḥ
Genitive	śirasyasya	śirasyayoḥ	śirasyānām
Locative	śirasye	śirasyayoḥ	śirasyeṣu

Compound śirasya -

Adverb -śirasyam -śirasyāt