Shiva Purana
ततः शक्रस्सुसन्नद्धस्तेन वज्रेण स द्रुतम् ॥ उच्चकर्त शिरो वार्त्रं गिरिशृंगमिवौजसा ॥ ३१ ॥
Indra who was well prepared, cut off the peaklike head of Vṛtra with the thunderbolt forcefully.
english translation
tataH zakrassusannaddhastena vajreNa sa drutam ॥ uccakarta ziro vArtraM girizRMgamivaujasA ॥ 31 ॥
hk transliteration by Sanscript