Natyashastra
अतालं च सतालं च द्विप्रकारं तदुच्यते । सतालं च ध्रुवाऽर्थेषु निबद्धं सर्वसाधकम् ॥ २९॥
It is said to be of two kinds: without time-measure (a-tāla) and with time-measure (sa-tāla). That which is with time-measure and regularly composed is fully appropriate for the purposes of the Dhruvā.
english translation
atAlaM ca satAlaM ca dviprakAraM taducyate । satAlaM ca dhruvA'rtheSu nibaddhaM sarvasAdhakam ॥ 29॥
hk transliteration by Sanscript