Shiva Purana
भ्रुवोर्मध्यं समारभ्य यावदंतो भवेद्भ्रुवोः । तावत्प्रमाणं संधार्यं ललाटे च त्रिपुंड्रकम् ८५ ।
The Tripuṇḍra on the forehead extends from the middle of the eyebrows to the tips of the brows on either side.
english translation
bhruvormadhyaM samArabhya yAvadaMto bhavedbhruvoH । tAvatpramANaM saMdhAryaM lalATe ca tripuMDrakam 85 ।
hk transliteration by Sanscript