Ayuda en línea Instituto Cervantes FAQ Current: Formats and Collections Formats and Collections The ebook I downloaded is not a PDF or EPUB file, but an ACSM file. What is it, and what software should I use to open it? Why are some books only available in EPUB format and others only in PDF format? Why are they sometimes available in both formats? Which one should I choose? Why are some commercially available ebooks not available on the platform? What's the difference between the EPUB and PDF format? A lot of books are already checked out. Is there a way to search for available books only? ×