Shiva Purana
राक्षसो गिरिधर्त्ता च महाबलपराक्रमः॥ लंकाख्यो दुर्गमो दुर्ग इंद्रजित्तनयोस्य वै॥ १२॥
He was a demon who lifted mountains and was very strong and valiant The fortress of Lanka is inaccessible to the sons of Indrajit.
english translation
rAkSaso giridharttA ca mahAbalaparAkramaH॥ laMkAkhyo durgamo durga iMdrajittanayosya vai॥ 12॥
hk transliteration by Sanscript