Natyashastra
अन्ते चाथ विशेषेण स्थाप्यमस्य हि शीर्षकम् । एवमङ्गविधिः कार्यः सप्तरूपे प्रयोक्तृभिः ॥ २१३॥
At the end, the Śīrṣaka should be specially placed. Thus the arrangement of the limbs is to be performed in the seven types of songs.
english translation
ante cAtha vizeSeNa sthApyamasya hi zIrSakam । evamaGgavidhiH kAryaH saptarUpe prayoktRbhiH ॥ 213॥
hk transliteration by Sanscript