Surya Siddhanta
तद्द्वादशसहस्राणि चतुर्युगम् उदाहृतम्। सूर्याब्दसम्ख्यया द्वित्रिसागरैर् अयुताहतैः ॥
The time containing twelve thousand years of the Gods is called a Chaturyuga (the aggregate of the four yugas, Krịta, Treṭá, Dwápara and Kali).
english translation
taddvAdazasahasrANi caturyugam udAhRtam। sUryAbdasamkhyayA dvitrisAgarair ayutAhataiH ॥
hk transliteration by Sanscript