Check the publisher's official website. They often sell "enhanced digital editions" which are essentially portable PDFs that are legally licensed and safe to download.
Sometimes, Google Books offers a significant preview of the text. While you won't get the whole book, you can often read the specific chapters you need for an upcoming assignment. medical microbiology michael ford pdf portable
Remember: In microbiology, the organism does not wait. Neither should your access to knowledge. Check the publisher's official website