Shiva Purana
स्वारोचिषेन्तरे पूर्वं विरथो नाम पार्थिवः ॥ सुरथस्तस्य पुत्रोऽभून्महाबलपराक्रमः ॥ १४ ॥
Formerly in the Svārociṣa Manvantara there was a king Viratha. Suratha his son was of great strength and exploit.
english translation
svArociSentare pUrvaM viratho nAma pArthivaH ॥ surathastasya putro'bhUnmahAbalaparAkramaH ॥ 14 ॥
hk transliteration by Sanscript