I seriously doubt that the website has permission from the publishers to put those books online. I'm fairly certain those are illegal copies -- don't use them! Support the Perl publishers and authors by buying your books. Several members of the monastery are Perl book authors and like everyone else they need to make a living -- I doubt they'd appreciate people pirating copies of their books. I know that merlyn, TheDamian, davorg, and chromatic have Perl related books out and I think japhy and Dominus have books on the way. There are probably other authors in our community too -- support the community, not pirate book sites.