Brihat Samhita
वीथीमार्गानपरे कथयन्ति यथास्थितान्भमार्गस्य । नक्षत्राणां तारा याम्योत्तरमध्यमास्तद्वत् ॥ ९-०५ ॥
According to some the position of a Vīthi follows that of the Yoga Tārā (chief star) of the particular constellation; so that if the star should be on the north of the ecliptic, the Vīthi is known as the northern one; if on the ecliptic, it is known as the central one and if on the south of the ecliptic, it is known as the southern one.
english translation
vIthImArgAnapare kathayanti yathAsthitAnbhamArgasya । nakSatrANAM tArA yAmyottaramadhyamAstadvat ॥ 9-05 ॥
hk transliteration by Sanscript