Shiva Purana
एते वाराह कल्पे ऽस्मिन्सप्तमस्यांतरो मनोः ॥ अष्टाविंशतिसंख्याता योगाचार्या युगक्रमात् ॥ ६ ॥
These are the seven intervals of Manu in the Vārāha kalpa. The yoga teachers are numbered twenty-eight in the order of the ages.
english translation
ete vArAha kalpe 'sminsaptamasyAMtaro manoH ॥ aSTAviMzatisaMkhyAtA yogAcAryA yugakramAt ॥ 6 ॥
hk transliteration by Sanscript