Instant purchase is OK. This is a set of 4 books that provide practical knowledge on cybersecurity and web application development. I will consider price negotiations and selling individual books if you inquire, so please feel free to ask. (Please note that I do not guarantee that I will accept your offer.) Product Description As shown in the images, some of the books have had their dust jackets discarded. Also, there are a few notes written in "How to Build a Hacking Lab," but they can be counted on one hand. The other three books haven't been read at all. They ended up being "tsundoku" (books that have been bought but not read). With the wave of DX (Digital Transformation) in the future, the demand for cybersecurity will increase. I believe that using this set of 4 books will be helpful for job hunting and career changes. - Title: How to Build a Hacking Lab Complete Edition (6820 yen) - Title: Cybersecurity Programming 2nd Edition (3520 yen) - Title: How to Build Secure Web Applications 2nd Edition (3520 yen) - Title: Hacking for Beginners in 7 Days (2860 yen)