Shiva Purana
तत्पद्मकर्णिकामध्ये कृत्वा लिंगं कनीयसम् ॥ स्फाटिकं पीठिकोपेतं पूजयेद्विधिवत्क्रमात् ॥ ३० ॥
In the middle of the pericarp a small crystal phallic image along with its pedestal shall be kept and worshipped.
english translation
tatpadmakarNikAmadhye kRtvA liMgaM kanIyasam ॥ sphATikaM pIThikopetaM pUjayedvidhivatkramAt ॥ 30 ॥
hk transliteration by Sanscript