Others may divide the whole planetary system into three divisions, namely the lower planetary systems on the legs [up to the earth], the middle planetary systems on the navel, and the upper planetary systems [Svarloka] from the chest to the head of the Supreme Personality.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
भूर्लोकः कल्पितः पद्भ्यां भुवर्लोकोऽस्य नाभितः । स्वर्लोकः कल्पितो मूर्ध्ना इति वा लोककल्पना
bhūrlokaḥ kalpitaḥ padbhyāṃ bhuvarloko'sya nābhitaḥ | svarlokaḥ kalpito mūrdhnā iti vā lokakalpanā
SB 2.5.42