Brihat Parashara Hora Shastra
धूम्राकारो नीलतनुर्वनस्थोऽपि भयंकरः। वातप्रकृतिको धीमान् स्वर्भानुस्तत्समः शिखी॥ ३०॥
Description of Rahu and Ketu. Rahu has smoky appearance with a blue mix physique. He resides in forests and is horrible. He is windy in temperament and is intelligent. Ketu is akin to Rahu.
english translation
dhUmrAkAro nIlatanurvanastho'pi bhayaMkaraH। vAtaprakRtiko dhImAn svarbhAnustatsamaH zikhI॥ 30॥
hk transliteration by Sanscript