I should check if the book is available in public libraries, through library services like OverDrive or Libby that offer e-books for free with a library card. Also, look into open educational resources or free textbooks provided by some universities or educational platforms. Maybe the publisher's website has a sample or chapter available for preview to see if it's what they need.
Also, portable might refer to having a portable version of the PDF, so maybe they want it in a format that's easy to carry on a device. Still, the key issue is getting the book legally. I should check if the book is available
Additionally, there are platforms like Google Books or Amazon where they can read a portion of the book for free. If the user is a student, they might have access through their school's library or academic resources. Some schools provide access to e-books via institutional subscriptions. Also, portable might refer to having a portable
Wait, the original query is in Spanish, so maybe the user is in a Spanish-speaking country. Some regions might have different access to digital resources, so I should consider that when suggesting alternatives. Maybe recommend Spanish educational portals or resources that are available in their region. If the user is a student, they might