SB 5.20.1
sri-suka uvaca
atah param plaksadinam pramana-laksana-samsthanato varsa-vibhaga upavarnyate.
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The great sage Sukadeva Gosvami said: Hereafter I shall describe the dimensions, characteristics and forms of the six islands beginning with the island of Plaksa.