Shiva Purana
नदीतीरे तडागे च पर्वते काननेऽपि च । शिवालये शुचौ देशे पार्थिवार्चा विधीयते ५ ।
The worship of the earthen phallic image shall be performed on the bank of a river or a tank or on the top of a mountain or in a forest, or in a Śiva temple. It must be in a clean place.
english translation
nadItIre taDAge ca parvate kAnane'pi ca । zivAlaye zucau deze pArthivArcA vidhIyate 5 ।
hk transliteration by Sanscript