Shiva Purana
लिंगं दर्शनमात्रं वा नियमेन शिवप्रदम् । मृत्पिष्टगोशकृत्पुष्पैः करवीरेण वा फलैः ३२ ।
Regular vision of the phallic emblem accords benefit. Or the devotee can make a phallic emblem out of clay, cow-dung, flowers, Karavīra fruit.
english translation
liMgaM darzanamAtraM vA niyamena zivapradam । mRtpiSTagozakRtpuSpaiH karavIreNa vA phalaiH 32 ।
hk transliteration by Sanscript