Brihat Samhita
चत्वारि मुख्यानि युगान्यथएषां विष्णुइन्द्रजीवानलदैवतानि । चत्वारि मध्यानि च मध्यमानि चत्वारि चान्त्यान्यधमानि विन्द्यात् ॥ ८-२६ ॥
In the first four yugas there will be prosperity in the land; in the next or middle four there will not be much of it; and in the last four mankind will suffer miseries.
english translation
catvAri mukhyAni yugAnyathaeSAM viSNuindrajIvAnaladaivatAni । catvAri madhyAni ca madhyamAni catvAri cAntyAnyadhamAni vindyAt ॥ 8-26 ॥
hk transliteration by Sanscript