SB 6.6.12

prāṇasyorjasvatī bhāryā
 saha āyuḥ purojavaḥ
dhruvasya bhāryā dharaṇir
 asūta vividhāḥ puraḥ
Word for word: 
prāṇasya — of Prāna; ūrjasvatī — Ūrjasvatī; bhāryā — the wife; sahaḥ — Saha; āyuḥ — Āyus; purojavaḥ — Purojava; dhruvasya — of Dhruva; bhāryā — the wife; dharaṇiḥ — Dharaṇi; asūta — gave birth to; vividhāḥ — the various; puraḥ — cities and towns.
Translation: 
Ūrjasvatī, the wife of Prāṇa, gave birth to three sons, named Saha, Āyus and Purojava. The wife of Dhruva was known as Dharaṇi, and from her womb various cities took birth.