Natyashastra
चतुरस्रस्तु विज्ञेयस्तालश्चञ्चूपुटो बुधैः । त्र्यस्रश्चञ्चूपुटश्चैव गुरुलघ्वक्षरान्वितः ॥ ९॥
The Cañcatpuṭa is known by the wise as the Caturasra (fourfold) Tāla, and the Cāpapuṭa is the Tryasra (threefold) one. Both consist of long (guru) and short (laghu) syllables.
english translation
caturasrastu vijJeyastAlazcaJcUpuTo budhaiH । tryasrazcaJcUpuTazcaiva gurulaghvakSarAnvitaH ॥ 9॥
hk transliteration by Sanscript