https://readanybooks.com/book/11044-the-sea-of-monsters
* Archivio testo completo - Percy Jackson e gli dei dell'Olimpo
https://archive.org/details/PercyJackson02_980
* Audiolibri LibriVox - Il mare dei mostri
https://librivox.org/the-sea-of-monsters-by-rick-riordan/