Natyashastra
विधिष्चतुष्कलो ज्ञेयः प्रागुक्ताङ्गुलिभिः कृतः । द्विकलश्चतुष्कलश्च पादभागः प्रकीर्तितः ॥ ५१॥
The proper method (of playing) with the previously mentioned fingers is to be known as consisting of four kalās; Two-kalā and four-kalā divisions are referred to as the quarter portion (pāda-bhāga).
english translation
vidhiScatuSkalo jJeyaH prAguktAGgulibhiH kRtaH । dvikalazcatuSkalazca pAdabhAgaH prakIrtitaH ॥ 51॥
hk transliteration by Sanscript