Brihat Parashara Hora Shastra
राहुश्चाण्डालजातिश्च केतुर्जात्यन्तरस्तथा। शिखिस्वर्भानुमन्दानां वल्मीकः स्थानमुच्यते॥ ४१॥
Other matters. Rahu rules the outcaste, while Ketu governs mixed caste. Śani and the nodes indicate ant-hills.
english translation
rAhuzcANDAlajAtizca keturjAtyantarastathA। zikhisvarbhAnumandAnAM valmIkaH sthAnamucyate॥ 41॥
hk transliteration by Sanscript