I've been looking into Buddhist concepts and the topic of infinite universes in existence popped up, and the Buddhist text called the "Abhidharmartha Pradipika" talks about infinite universes? And I was wondering what chapter/verse talks about it so I could look more into it.
Abhidharmarthapradipika can be read here in four volumes, but it is all in Sinhalese. You will need to find a translator or someone who can read it for you. I don't know if it has been translated.
The rest of the volumes are on the first link.