Shiva Purana
एवं त्र्यावरणं देवं समभ्यर्च्य दिवाकरम् ॥ विरच्य मंडलं पश्चाच्चतुरस्रं समाहितः ॥ ३५ ॥
Thus worshiping the sun-god who covered the three worlds He formed a circle and concentrated on the four sides of the back.
english translation
evaM tryAvaraNaM devaM samabhyarcya divAkaram ॥ viracya maMDalaM pazcAccaturasraM samAhitaH ॥ 35 ॥
hk transliteration by Sanscript