One verse

Srimad Bhagavatam 2.5.42

2.5.42

भूर्लोक: कल्पित: पद्‍भ्यां भुवर्लोकोऽस्य नाभित: । स्वर्लोक: कल्पितो मूर्ध्ना इति वा लोककल्पना ॥ ४२ ॥

bhurlokah kalpitah padbhyam bhuvarloko ’sya nabhitah svarlokah kalpito murdhna iti va loka-kalpana

bhurlokah
the entire planetary system from Patala to the earthly planetary system
kalpitah
imagined
padbhyam
situated on the legs
bhuvarlokah
the Bhuvarloka planetary system
asya
of the universal form of the Lord
nabhitah
out of the navel abdomen
svarlokah
the higher planetary system, beginning with the heavenly planets
kalpitah
imagined
murdhna
from the chest to the head
iti
thus
va
either
loka
the planetary systems
kalpana
imagination

Others may divide the whole planeary system into three divisions, namely the lower planeary 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.