Brihat Parashara Hora Shastra
रसाः पञ्चेन्दवो नागाः सप्तचन्द्राश्च खेन्दवः । गोऽब्जाः सूर्याः कुनेत्राश्च रव्यादीनां दशासमाः ॥ २०॥
6, 15, 8, 17, 10, 19, 12 and 21 in that order. Thus in this Dasha system only 8 Grahas play the role of Dasha Lords, Ketu having been denied this privilege.
english translation
rasAH paJcendavo nAgAH saptacandrAzca khendavaH । go'bjAH sUryAH kunetrAzca ravyAdInAM dazAsamAH ॥ 20॥
hk transliteration by Sanscript