If you have doubts about an ebook, then the simplest way is to check its reviews. You can do this through Google. Access the search engine and type book name + review or book name preview. The first one will give you details about other's users opinions about the book, and the second one will provide a sample preview of the book, then you can figure it out by youself. If it's offered to download the PDF, then use a compatible ebook reader.