Brihat Samhita
दर्पणवृत्तऽकारा विशिखाः किरणान्विता धरातनयाः । क्षुद्भयदा द्वाविंशतिरैशान्यां अम्बुतैलनिभाः ॥ ११-१३ ॥
The Ketus or comets that appear like a mirror, are round in shape without tails but with rays and looking like oil or water are the sons of the Earth; they are 23 in number, and appear in the north-east; when they appear mankind will be afflicted with fear and hunger.
english translation
darpaNavRtta'kArA vizikhAH kiraNAnvitA dharAtanayAH । kSudbhayadA dvAviMzatiraizAnyAM ambutailanibhAH ॥ 11-13 ॥
hk transliteration by Sanscript