Shiva Purana
अलब्धे स्थापिते लिंगे शिवस्थाने जले ऽथ वा ॥ वह्नौ रवौ तथा व्योम्नि भगवंतं शिवं यजेत् ॥ ७० ॥
If an installed Liṅga is not available, he shall worship the lord in a place sacred to Śiva, or in water, fire, the sun or the sky.
english translation
alabdhe sthApite liMge zivasthAne jale 'tha vA ॥ vahnau ravau tathA vyomni bhagavaMtaM zivaM yajet ॥ 70 ॥
hk transliteration by Sanscript