Shiva Purana
पृष्ठतोऽस्तगिरिश्चैव ह्यविकेशश्च केसरी ॥ शाकस्तत्र महावृक्षस्सिद्धगंधर्वसेवितः ॥ ५३॥
Behind him are Astagiri and Hyavikesha and Kesari There is a huge tree called Shaka inhabited by siddhas and gandharvas.
english translation
pRSThato'stagirizcaiva hyavikezazca kesarI ॥ zAkastatra mahAvRkSassiddhagaMdharvasevitaH ॥ 53॥
hk transliteration by Sanscript